n.medical Latin, from Greek amastos "without breasts," from privative prefix a- (see a- (3)) + mastos "breast" (see masto-) + -ia. if (window.googletag) {googletag.cmd.push(function() { googletag.display('dcomMobileSERPDisplayTopAd-300x250'); });} else {console.error('googletag not defined, dcomMobileSERPDisplayTopAd-300x250');} n. Congenital absence of one or both breasts.amazia