mastoid (adj.)youdaoicibaDictYouDict[mastoid 词源字典]
"breast-shaped, resembling a breast or nipple," 1732, from Greek mastoeides "resembling a breast," from mastos "(woman's) breast" (see masto-) + -oeides "like," from eidos "form, shape" (see -oid). As a noun, 1800, from the adjective.[mastoid etymology, mastoid origin, 英语词源]