mastoid

The story

1. Ancient Greek · derived fromμᾰστοειδής“like a breast”
2. New Latin · borrowed frommastoīdēs
3. English todaymastoid

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