mastoides

Borrowed from Ancient Greek μᾰστοειδής (măstoeidḗs, “like a breast”), from μᾰστός (măstós, “a woman's breast”) +‎ -ειδής (-eidḗs, “-like, -oid”).

• (modern Italianate Ecclesiastical) IPA^(key): [mas.toˈiː.des]

mastoīdēs (neuter mastoīdes); third-declension one-termination adjective (Greek-type) (New Latin)

1. Shaped like a breast.

Third-declension one-termination adjective (Greek-type).

¹It is unknown whether adjectives of this type would use i-stem or consonant-stem endings in Classical Latin: the relevant forms are not attested. Depending on the word, either ending or both may be attested in New Latin.

• sternocleidomastoīdēs
• sternocleidomastoīdeus

• → English: mastoid
• → Spanish: mastoides

• IPA^(key): /masˈtoides/ [masˈt̪oi̯.ð̞es]
• Rhymes: -oides
• Syllabification: mas‧toi‧des

mastoides (invariable)

1. (anatomy) mastoid

   Synonym: mastoideo

mastoides m (plural mastoides)

1. (anatomy) mastoid; mastoid process

• “mastoides”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025