- a combining form meaning “breast,” used in the formation of compound words: mastopathy.
Origin of masto-
before a vowel mast-
- indicating the breast, mammary glands, or something resembling a breast or nipplemastodon; mastoid
Word Origin and History for masto-
before vowels mast-, word-forming element meaning "breast," from comb. form of Greek mastos "woman's breast," from madan "to be wet, to flow," from PIE *mad- "wet, moist, dripping" (cf. Latin madere "be moist;" Albanian mend "suckle;" see mast (n.2)).
- Breast; mammary gland; nipple:mastectomy.