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1. The absence or closure of a normal body orifice or tubular passage such as the anus, intestine, or external ear canal.
2. The degeneration and resorption of one or more ovarian follicles before a state of maturity has been reached.
[New Latin atrēsia : Greek a-, not, without; see a-1 + Greek trēsis, perforation, orifice; see terə- in Indo-European roots.]
a·tre·sic (-zĭk, -sĭk) adj.
marked by atresia