"-ειν" meaning in Ancient Greek

{
  "etymology_templates": [
    {
      "args": {
        "1": "grc",
        "2": "grk-pro",
        "3": "*-ehen"
      },
      "expansion": "Proto-Hellenic *-ehen",
      "name": "inh"
    },
    {
      "args": {
        "1": "grc",
        "2": "ine-pro",
        "3": "*-os",
        "4": "*-esen"
      },
      "expansion": "Proto-Indo-European *-esen",
      "name": "inh"
    },
    {
      "args": {
        "1": "la",
        "2": "-ere"
      },
      "expansion": "Latin -ere",
      "name": "cog"
    }
  ],
  "etymology_text": "Seen in thematic verbs it may be from Proto-Hellenic *-ehen, from Proto-Indo-European *-esen, locative case of action noun. Similar to Latin -ere. See also -εναι (-enai), -έμεν (-émen), -μεναι (-menai).",
  "forms": [
    {
      "form": "-ein",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "grc",
        "2": "suffix"
      },
      "expansion": "-ειν • (-ein)",
      "name": "head"
    }
  ],
  "lang": "Ancient Greek",
  "lang_code": "grc",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Ancient Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "infinitive forming suffix"
      ],
      "id": "en--ειν-grc-suffix-R5d1Sc~a",
      "links": [
        [
          "infinitive",
          "infinitive"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/eːn/"
    },
    {
      "ipa": "/in/"
    },
    {
      "ipa": "/in/"
    },
    {
      "ipa": "/eːn/",
      "note": "5ᵗʰ BCE Attic"
    },
    {
      "ipa": "/in/",
      "note": "1ˢᵗ CE Egyptian"
    },
    {
      "ipa": "/in/",
      "note": "4ᵗʰ CE Koine"
    },
    {
      "ipa": "/in/",
      "note": "10ᵗʰ CE Byzantine"
    },
    {
      "ipa": "/in/",
      "note": "15ᵗʰ CE Constantinopolitan"
    }
  ],
  "word": "-ειν"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "grc",
        "2": "grk-pro",
        "3": "*-ehen"
      },
      "expansion": "Proto-Hellenic *-ehen",
      "name": "inh"
    },
    {
      "args": {
        "1": "grc",
        "2": "ine-pro",
        "3": "*-os",
        "4": "*-esen"
      },
      "expansion": "Proto-Indo-European *-esen",
      "name": "inh"
    },
    {
      "args": {
        "1": "la",
        "2": "-ere"
      },
      "expansion": "Latin -ere",
      "name": "cog"
    }
  ],
  "etymology_text": "Seen in thematic verbs it may be from Proto-Hellenic *-ehen, from Proto-Indo-European *-esen, locative case of action noun. Similar to Latin -ere. See also -εναι (-enai), -έμεν (-émen), -μεναι (-menai).",
  "forms": [
    {
      "form": "-ein",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "grc",
        "2": "suffix"
      },
      "expansion": "-ειν • (-ein)",
      "name": "head"
    }
  ],
  "lang": "Ancient Greek",
  "lang_code": "grc",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        "Ancient Greek 1-syllable words",
        "Ancient Greek entries with incorrect language header",
        "Ancient Greek lemmas",
        "Ancient Greek suffixes",
        "Ancient Greek terms derived from Proto-Hellenic",
        "Ancient Greek terms derived from Proto-Indo-European",
        "Ancient Greek terms inherited from Proto-Hellenic",
        "Ancient Greek terms inherited from Proto-Indo-European",
        "Ancient Greek terms with IPA pronunciation"
      ],
      "glosses": [
        "infinitive forming suffix"
      ],
      "links": [
        [
          "infinitive",
          "infinitive"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/eːn/"
    },
    {
      "ipa": "/in/"
    },
    {
      "ipa": "/in/"
    },
    {
      "ipa": "/eːn/",
      "note": "5ᵗʰ BCE Attic"
    },
    {
      "ipa": "/in/",
      "note": "1ˢᵗ CE Egyptian"
    },
    {
      "ipa": "/in/",
      "note": "4ᵗʰ CE Koine"
    },
    {
      "ipa": "/in/",
      "note": "10ᵗʰ CE Byzantine"
    },
    {
      "ipa": "/in/",
      "note": "15ᵗʰ CE Constantinopolitan"
    }
  ],
  "word": "-ειν"
}