Why was "tantrum" trending last week?
"encysted tumor," 1706, medical Latin, from Greek atheroma, from athere "groats, porridge" (related to ather "chaff"), in reference to what is inside. For ending, see -oma.
atheroma ath·er·o·ma (āth'ə-rō'mə)n. pl. ath·er·o·mas or ath·er·o·ma·ta (-mə-tə) A deposit or degenerative accumulation of lipid-containing plaques on the innermost layer of the wall of an artery.