"εὐ-" meaning in Ancient Greek

{
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "en",
            "2": "eu-"
          },
          "expansion": "English: eu-",
          "name": "desc"
        }
      ],
      "text": "English: eu-"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "grc",
        "2": "εὖ>well",
        "id": "well"
      },
      "expansion": "",
      "name": "etymon"
    }
  ],
  "etymology_text": "Prefix form of εὖ (eû, “well”).",
  "forms": [
    {
      "form": "eu-",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "grc",
        "2": "prefix"
      },
      "expansion": "εὐ- • (eu-)",
      "name": "head"
    }
  ],
  "lang": "Ancient Greek",
  "lang_code": "grc",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Ancient Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "good, well"
      ],
      "id": "en-εὐ--grc-prefix-AZpyhbGd",
      "links": [
        [
          "good",
          "good"
        ],
        [
          "well",
          "well"
        ]
      ],
      "synonyms": [
        {
          "roman": "eü-",
          "tags": [
            "Epic"
          ],
          "word": "ἐϋ-"
        }
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/eu̯/"
    },
    {
      "ipa": "/eβ/"
    },
    {
      "ipa": "/ev/"
    },
    {
      "ipa": "/eu̯/",
      "note": "5ᵗʰ BCE Attic"
    },
    {
      "ipa": "/ew/",
      "note": "1ˢᵗ CE Egyptian"
    },
    {
      "ipa": "/eβ/",
      "note": "4ᵗʰ CE Koine"
    },
    {
      "ipa": "/ev/",
      "note": "10ᵗʰ CE Byzantine"
    },
    {
      "ipa": "/ev/",
      "note": "15ᵗʰ CE Constantinopolitan"
    }
  ],
  "word": "εὐ-"
}

{
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "en",
            "2": "eu-"
          },
          "expansion": "English: eu-",
          "name": "desc"
        }
      ],
      "text": "English: eu-"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "grc",
        "2": "εὖ>well",
        "id": "well"
      },
      "expansion": "",
      "name": "etymon"
    }
  ],
  "etymology_text": "Prefix form of εὖ (eû, “well”).",
  "forms": [
    {
      "form": "eu-",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "grc",
        "2": "prefix"
      },
      "expansion": "εὐ- • (eu-)",
      "name": "head"
    }
  ],
  "lang": "Ancient Greek",
  "lang_code": "grc",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        "Ancient Greek 1-syllable words",
        "Ancient Greek entries with incorrect language header",
        "Ancient Greek lemmas",
        "Ancient Greek prefixes",
        "Ancient Greek terms derived from Proto-Hellenic",
        "Ancient Greek terms derived from Proto-Indo-European",
        "Ancient Greek terms derived from the Proto-Indo-European root *h₁es-",
        "Ancient Greek terms inherited from Proto-Hellenic",
        "Ancient Greek terms inherited from Proto-Indo-European",
        "Ancient Greek terms with IPA pronunciation",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "good, well"
      ],
      "links": [
        [
          "good",
          "good"
        ],
        [
          "well",
          "well"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/eu̯/"
    },
    {
      "ipa": "/eβ/"
    },
    {
      "ipa": "/ev/"
    },
    {
      "ipa": "/eu̯/",
      "note": "5ᵗʰ BCE Attic"
    },
    {
      "ipa": "/ew/",
      "note": "1ˢᵗ CE Egyptian"
    },
    {
      "ipa": "/eβ/",
      "note": "4ᵗʰ CE Koine"
    },
    {
      "ipa": "/ev/",
      "note": "10ᵗʰ CE Byzantine"
    },
    {
      "ipa": "/ev/",
      "note": "15ᵗʰ CE Constantinopolitan"
    }
  ],
  "synonyms": [
    {
      "roman": "eü-",
      "tags": [
        "Epic"
      ],
      "word": "ἐϋ-"
    }
  ],
  "word": "εὐ-"
}