ronna-

Blend of r (an arbitrarily chosen initial letter) + Ancient Greek ἐννέα (ennéa, “nine”) + -a (to match the final letter of the SI prefixes from mega- upwards).
Coined by Richard J. C. Brown and adopted by the General Conference on Weights and Measures in 2022 as an expansion to the metric prefixes beyond 10^(±24).
Some popular unofficial terms already in use were hella-, bronto- and xenna-, but terms beginning with the same letters as existing prefixes were considered undesirable, as were as those beginning with common scientific letters such as b or x. Richard J. C. Brown suggested that the new terms begin with r and q, due to their rarity as unit symbols, and that the trends followed by the other prefixes be continued: that they be based on Latin or Greek; that large prefixes end with -a and small prefixes end with -o; that they should be in corresponding large and small pairs; and that the first letters of each prefix should be in reverse alphabetical order (as has been the case for the newer prefixes). He therefore suggested ronna- and ronto- (evoking Ancient Greek ἐννέα (ennéa) and Latin novem (“nine”)), and quecca- and quecto- (evoking Ancient Greek δέκα (déka) and Latin decem (“ten”)), because as 10²⁷ and 10³⁰ when written have nine and ten groups of zeroes, respectively. These were adopted, with quecca- changed to quetta-.

blend

In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10²⁷ (a short scale octillion or long scale quadrilliard). Symbol: R


quecto-

Blend of q (an arbitrarily chosen initial letter) + Latin decem (“ten”) + -to (to match the final syllable of the SI prefixes from femto- downwards).
Coined by Richard J. C. Brown and adopted by the General Conference on Weights and Measures in 2022 as an expansion to the metric prefixes beyond 10^(±24).
Some popular unofficial terms already in use were hella-, bronto- and xenna-, but terms beginning with the same letters as existing prefixes were considered undesirable, as were as those beginning with common scientific letters such as b or x. Richard J. C. Brown suggested that the new terms begin with r and q, due to their rarity as unit symbols, and that the trends followed by the other prefixes be continued: that they be based on Latin or Greek; that large prefixes end with -a and small prefixes end with -o; that they should be in corresponding large and small pairs; and that the first letters of each prefix should be in reverse alphabetical order (as has been the case for the newer prefixes). He therefore suggested ronna- and ronto- (evoking Ancient Greek ἐννέα (ennéa) and Latin novem (“nine”)), and quecca- and quecto- (evoking Ancient Greek δέκα (déka) and Latin decem (“ten”)), because as 10²⁷ and 10³⁰ when written have nine and ten groups of zeroes, respectively. These were adopted, with quecca- changed to quetta-.

to match the final syllable of the SI prefixes from <i class="Latn mention" lang="en">femto-</i> downwards

2022 SI prefixes

International System of Units
International System of Units

In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻³⁰ (short scale nonillionth or long scale quintillionth). Symbol: q


ronto-

Blend of r (an arbitrarily chosen initial letter) + Ancient Greek ἐννέα (ennéa, “nine”) + -to (to match the final syllable of the SI prefixes from femto- downwards).
Coined by Richard J. C. Brown and adopted by the General Conference on Weights and Measures in 2022 as an expansion to the metric prefixes beyond 10^(±24).
Some popular unofficial terms already in use were hella-, bronto- and xenna-, but terms beginning with the same letters as existing prefixes were considered undesirable, as were as those beginning with common scientific letters such as b or x. Richard J. C. Brown suggested that the new terms begin with r and q, due to their rarity as unit symbols, and that the trends followed by the other prefixes be continued: that they be based on Latin or Greek; that large prefixes end with -a and small prefixes end with -o; that they should be in corresponding large and small pairs; and that the first letters of each prefix should be in reverse alphabetical order (as has been the case for the newer prefixes). He therefore suggested ronna- and ronto- (evoking Ancient Greek ἐννέα (ennéa) and Latin novem (“nine”)), and quecca- and quecto- (evoking Ancient Greek δέκα (déka) and Latin decem (“ten”)), because as 10²⁷ and 10³⁰ when written have nine and ten groups of zeroes, respectively. These were adopted, with quecca- changed to quetta-.

blend

In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻²⁷ (short scale octillionth or long scale quadrilliardth). Symbol: r


lyc-

Alternative form of lyco- (before a vowel)


lyco-

From Ancient Greek λύκος (lúkos, “wolf”).


onych-

Alternative form of onycho- (before a vowel)


koilo-

From international scientific vocabulary, reflecting a New Latin combining form, from Ancient Greek κοῖλο- (koîlo-, “hollow, concave”).

der

classical compound
international scientific vocabulary


numero-

Borrowed from Latin numerus (“number”) + -o-.

numero- + -logy → numerology

numero- + -phobia → numerophobia

numero- + -nym → numeronym


rhiz-

Alternative form of rhizo- (before a vowel)


naphtho-

(organic chemistry) Formally describing any compound in which a naphthalene molecule has been fused to another ring molecule.

(organic chemistry) Used for some derivative of naphthalene.


ile-

Alternative form of ileo- (before a vowel)


oesophag-

(digraph, especially UK) Alternative form of esophago-


aetio-

(digraph, especially UK) Alternative form of etio-


esophag-

Alternative form of esophago- (before a vowel)


etio-

From international scientific vocabulary, reflecting a New Latin combining form, from Ancient Greek roots; more at aetiology § Etymology.

(biology, medicine) cause; causes; causation.


tendo-

See tendo § Etymology and teno- § Etymology.


chaeto-

From international scientific vocabulary, reflecting a New Latin combining form; see English chaeta and New Latin chaeta, from Ancient Greek χαίτη (khaítē, “crest, mane, flowing hair, foliage”).

uder

(biology, medicine) chaeta (“chitinous bristle”).


cythero-

From Ancient Greek Κύθηρα (Kúthēra, “Cythera”).


planeto-

planeto- + -centric → planetocentric

Used to form astronomical terms related to planets


hepatico-

From hepatic (“relating to the liver”) + -o-.

hepatico- + jejunal → hepaticojejunal

hepatico- + pulmonary → hepaticopulmonary

hepatico- + biliary → hepaticobiliary

Synonym of hepato- (“relating to the liver”).

hepatico- + -logy → hepaticology

hepatico- + -logist → hepaticologist


endothelio-

endothelio- + chorial → endotheliochorial

endothelio- + -sis → endotheliosis

endothelio- + -cyte → endotheliocyte


hemangio-

Compound of hem- (“blood”) + angio- (“vessel”).

com+

hemangio- + blast → hemangioblast

hemangio- + -oma → hemangioma

hemangio- + sarcoma → hemangiosarcoma

(medicine) Relating to the blood vessels.


Burmo-

the Burmo-Chinese frontier


caeco-

From international scientific vocabulary, reflecting a New Latin combining form, from Latin caecum, as at caecum § Etymology.


papyro-

From combining forms of Ancient Greek πάπυρος (pápuros, “papyrus, paper”).

bor

Of, similar to, or related to papyrus or things made from papyrus.

Of, similar to, or related to paper or things made from paper such as paperwork.


dicho-

From Ancient Greek δῐ́χᾰ (díkha, “apart”).


Lusitano-

Lusitano-Spanish

Lusitano-American


tru-

tru- + fan → trufan

tru- + trans → trutrans


Franken-

Alternative letter-case form of franken-


soleno-

From Ancient Greek σωλήν (sōlḗn, “channel, syringe”).

der

Having a cavity by which something can pass, like venom


Guiano-

the Guiano-Brazilian subregion


Himalo-

the Himalo-Chinese subregion

Himalo-Caucasian


anatomo-

[The CT scanner and the temporomandibular joint. Anatomo-radiologic comparisons. Apropos of 14 cases of algodysfunctional of the manducator system] Vanneroy F, et al. J Radiol 1989 Feb;70(2):127-32 (Eng. Abstr.)

1989, Cumulated Index Medicus (NIH Publication No. 90-259), volumes 30, 1989, subject index Sp-Z, Bethesda, Md.: National Library of Medicine, →ISSN, page 12558, column 1:


thigmo-

From Ancient Greek θῐ́γμᾰ (thígma) + -o-, from the root of θῐγγᾰ́νω (thingánō, “to touch”).

thigmo- + tropism (“movement, turning”) → thigmotropism (“movement of a plant because of touching”)

(biology, botany) related to touching, usually a plant.


Carpatho-

the Carpatho-Russian people


racio-

racio- + linguistics → raciolinguistics

racio- + -logy → raciology


quecca-

Original proposed prefix for 10³⁰, but replaced with quetta- in the final plan due to a high resemblance to the Portuguese obscenity queca.


Sumero-

Sumero-Akkadian

Sumero-Babylonian


symmetro-

symmetro- + -phobia → symmetrophobia

symmetro- + -phile → symmetrophile

symmetro- + -logical → symmetrological


Moravo-

the Moravo-Silesian Belt


cost-

Alternative form of costo- (before a vowel)


mathematico-

[…] a mathematico-deductivist view […]

2003, Deborah A. Redman, The Rise of Political Economy as a Science, page 346:

[…] a mathematico-philosophical puzzle […]

2013, C. Sasaki, Descartes’s Mathematical Thought, page 98:


scientifico-

If he has a dogma, i.e. a scientifico-philosophical theory, then he is not any sort of Skeptic, not even an urbane Skeptic.

2015, Tad Brennan, Ethics and Epistemology in Sextus Empiricus:


geop-

Unknown, possibly from Korean 겁 (geop), referring to a very long period of time.

(computing, informal, nonstandard) Synonym of quetta-


duplo-

duplo- + carburet → duplocarburet

duplo- + sulphacetone → duplosulphacetone


duplicato-

Representing Latin duplicātō (“double, twice as much”, adverb).

bor

duplicato- + dentate → duplicato-dentate

duplicato- + pinnate → duplicato-pinnate

duplicato- + serrate → duplicato-serrate

duplicato- + ternate → duplicato-ternate

(prefixed to adjectives, chiefly botany) doubly


erem-

From Ancient Greek ἐρῆμος (erêmos, “lonesome, solitary”).


glucurono-

(biochemistry) Relating to glucuronic acid.


sado-

From the name of the Marquis de Sade, initially used to form words like sadism and later extrapolated into a prefix.

sadomasochism, sadopopulism, sadostate, sadosociety, sadoasceticism, sadoreligion, sadospiritual


Basco-

The Basque, for example, foreign in origin both to French and Spanish, has indeed been altered through the adoption of a few words and a few locutions borrowed from these languages, by which it is surrounded, and, as it were, invested; but it evermore clings to the basis of its structure, the vital principle of its organism; and a Franco-Basque, or a Basco-Spanish, is not spoken, nowhere has ever been spoken.

1857, [Louis Ferdinand] Alfred Maury, “On the Distribution and Classification of Tongues,—Their Relation to the Geographical Distribution of Races; and on the Inductions Which May Be Drawn from These Relations”, in Indigenous Races of the Earth; or, New Chapters of Ethnological Enquiry; […], Subscriber’s Copy, Philadelphia, Pa.: J[oshua] B[allinger] Lippincott & Co.; London: [Nicholas] Trübner & Co., section II, page 35:

If to this be added the ‘Euscaratik Erderara Biurtzeco Iztegia,’ or Basco-Spanish dictionary, by the late D. Francisco de Aizquivel, of which two parts have already appeared at Tolosa, and the recent treatise on Basque proper names (‘Los Apellidos Vascongados’) by Irigoyen, there is a good chance for us Castilians to penetrate into the mysteries of a language which is said to be the same that Noah and his sons spoke within the Ark, and has hitherto been, and will most likely continue to be, a puzzle to European philologists.

1882 December 30, J[uan] F[acundo] Riaño, “[Continental Literature in 1882.] Spain.”, in The Athenæum: Journal of Literature, Science, the Fine Arts, Music, and the Drama, number 2879, London: […] John C. Francis. […], page 893, column 2:


Lechito-

Lechito-Rani


Chukotko-

Chukotko-Kamchatkan


Corso-

Corso-Sardinian


Phrygio-

Relating to Phrygia, the Phrygians or the Phrygian language.


Checheno-

the Checheno-Ingush Autonomous Soviet Socialist Republic


Aryo-

Aryo-Dravidian

Aryo-Indian


volcan-

(geology) pertaining to volcanos or volcanology.


eteo-

Learned borrowing from Ancient Greek ἐτεός (eteós, “true, original”).

lbor

Eteo-Tocharian is a good example of the influence of Greeks in Central Asia. Eteo-Tocharian was written in a modified Greek alphabet (Maricq 1958:398). This script is a manifestation of the Greek influence in Bactria, even after the Kushana subjugation of this area.

2010, Clyde Winters, “Greek Influence on Sanskrit Language”, in Journal of Eurasian Studies, volume 2, number 3, archived from the original on 2024-02-17:

Bái vocabulary, later Chinese borrowings excluded, can be divided into a Sino-Bái vocabulary, which shows a close resemblance to Chinese, and a Pre-Bái or Eteo-Bái vocabulary, which is not etymologizable into Chinese.

2015, Xun Gong, “How Old is the Chinese in Bái?”, in Recent Advances in Old Chinese Historical Phonology Workshop, archived from the original on 2021-03-05:

(linguistics) Denoting an ancient or ancestral language (or form of a language), dating from a time before it came into contact with another language; particularly one which had considerable influence, or which later displaced it entirely.


bronchi-

(anatomy) (combining form) relating to bronchi


agr-

“agr-”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.

Alternative form of agri- or agro- (before a vowel).


eosin-

Ancient Greek ἠώς (ēṓs), dawn, daybreak, morning red, goddess of the dawn (Ἠώς, Ēṓs)


cardi-

“cardi-”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.


astr-

“astr-”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.

Alternative form of astr- (before a vowel).


thorough-

A variant of through-, common in 16th-19th centuries, particularly where there is a perceived connection with thorough “thorough-”, in OED Online , Oxford, Oxfordshire: Oxford University Press, launched 2000..

thoroughfare, thoroughgo, thoroughlane

thoroughgoingly, thoroughbreed, thoroughpaced

(non-productive) fully, completely; purely


lesbo-

lesbophobe is one who hates or has a negative perception of lesbians, lesbophilia is a fetishistic fascination (typically in non-lesbians) with lesbians and erotic contact between women, lesbosexual is someone who adopts the style associated with stereotypic lesbians


double-

(obsolete) In the metric system, multiplies the attached unit by two.


hebdo-

From Ancient Greek ἕβδομος (hébdomos, “seventh”).

der

(obsolete) In the metric system, multiplies the attached unit by 10⁷.


stephano-

From Ancient Greek στέφανος (stéphanos, “wreath”).


-coelous

From Ancient Greek κοῖλος (koîlos, “hollow”).


triple-

Three, or multipled by a factor of three.


fluora-

IUPAC Commission of Nomenclature for Heterocyclic Compounds (1957)

Indicating a heterocyclic compound with fluorine substitution


gloeo-

Derived from Ancient Greek γλοιός (gloiós).

der+

gloeo- + vessel → gloeovessel

gloeo- + cystidium → gloeocystidium

(biology) Having the character of glue; sticky.


enneakis-

(mathematics) A variant of ennea-, used for multiplication with a second numerical prefix.

(chemistry) A variant of ennea-, used for substitutions of nine complex rather than simple units.


somn-

From Latin somnus (“sleep, slumber”), from Proto-Indo-European *swépnos.


dictyo-

From Ancient Greek δίκτυον (díktuon, “net”).


aletho-

From Ancient Greek ἀλήθεια (alḗtheia, “truth”).


dodec-

Alternative form of dodeca- used before a vowel.


heptadec-

Alternative form of heptadeca- used before a vowel.


hexadec-

Alternative form of hexadeca- used before a vowel.


tetradec-

Alternative form of tetradeca- used before a vowel.


nonadec-

Alternative form of nonadeca- used before a vowel.


pentadec-

Alternative form of pentadeca- used before a vowel.


tridec-

Alternative form of trideca- used before a vowel.


undec-

Alternative form of undeca- used before a vowel.


octadec-

Alternative form of octadeca- used before a vowel.


eicos-

Alternative form of eicosa- used before a vowel.


-phane

Borrowed from Ancient Greek -φανής (-phanḗs, “having a certain appearance”).


nekto-

Combining form of nekton, from German Nekton which was coined in 1890 by Ernst Haeckel, from Ancient Greek νηκτόν (nēktón, “swimming”).


physo-

From Ancient Greek φῦσα (phûsa, “bladder”) or from φῡσᾰ́ω (phūsáō, “to blow, to puff”).

A combining form meaning “bladder,” used in the formation of compound words.


phobo-

From Ancient Greek φόβος (phóbos, “fear”).


acetabulo-

From international scientific vocabulary, reflecting a New Latin combining form, from acetabulum (which see for more).

(anatomy, medicine) acetabulum; acetabular.


syndesmo-

From Ancient Greek σύνδεσμος (súndesmos, “binding, fastening, ligament”).


De-

De- + Shawna → DeShawna

De- + Angelo → DeAngelo

De- + Andre → DeAndre

(US, African-American Vernacular, anthroponymy) Unisex prefix used in African-American given names.


fracto-

Borrowed from French fracto-, from Latin frāctus (“broken”).

fracto- + emission → fractoemission (“the generation of charge through the breakup of rock particles”)

Forming terms relating to the fracture or breaking of something.


pelvi-

From international scientific vocabulary, reflecting a New Latin combining form, from Latin pēlvis (“basin”).

pelvimeter

pelviureteric


juveno-

Borrowed from Latin iuvenis, juvenis (“young; youth”).

Forming terms relating to youth or young people.


Russio-

Mr. Tchoubinof, employed in foreign affairs in St. Petersburg, and a Georgian by birth, has edited a Georgio-Russio-French Dictionary,²⁸ infinitely richer than vocabularies we previously possessed.

1842, E. Roer, “Report made by J. Mohl in the General Meeting of the Asiatic Society of Paris, 31st May, 1841 […], translated from the French”, in Journal of the Asiatic Society of Bengal (New Series), volume 11, number 125, Calcutta: Bishop's College Press, page 431:


mani-

From many; and also continuing Middle English mani-, mæni-, maniȝ- (also moni-, moniȝ-), from Old English maniġ-, meniġ-, maneġ- (“many-, multi-”), from Proto-West Germanic *managa-, *manīga- (“many-, multi-”), from Proto-Germanic *managaz (“many”). Cognate with Old Frisian manich-, monich- (“many-”), Old Dutch manag- (“many-”), Old Saxon manag- (“many-”), Old High German manag- (“many-”), modern German manch- (“many-, some-”).

manicoloured, manifaceted, manifold, manisided, maniverse

Alternative spelling of many used in combination with nouns to form other nouns and adjectives


spongio-

From Ancient Greek σπογγιά (spongiá, “sponge”).

Relating to sponges or a spongy substance.


caec-

(biology, medicine) Alternative form of caeco-


kato-

From Ancient Greek κάτω (kátō, “downwards, below”).


noci-

From Latin noceo (“hurt”). First used in nociception.

(physiology) Relating to pain and its perception.


molybdo-

combining form of molybdenum, used to indicate that a substance or compound contains molybdenum