| n. | 1. | (Med.) Absence or closure of a natural passage or channel of the body; imperforation. |
| Noun | 1. | atresia - an abnormal condition in which a normal opening or tube in the body (as the urethra) is closed or absent |
Lack of a normal opening from the esophagus, intestines, or anus.
abnormal condition, abnormalcy, abnormality