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"occlusion of a natural passage in the body," 1807, from Modern Latin atresia, from Greek atretos "not perforated," from a-, privative prefix, + tresis "perforation," from PIE *tere- "to rub, turn," with derivatives referring to boring and drilling (see throw (v.)).
atresia a·tre·sia (ə-trē'zhə, -zhē-ə)
The congenital absence or closure of a normal body orifice or tubular passage such as the anus, intestine, or external ear canal.
The degeneration and resorption of one or more ovarian follicles before maturation.