imperforate (im-per-fer-it) adj. lacking an opening. i. anus (proctatresia) partial or complete obstruction of the anus: a condition, discovered at birth, due to failure of the anus to develop normally in the embryo. Most mild cases of imperforate anus can be treated by a simple operation. i. hymen a condition in which the hymen completely closes the vagina and thus impedes the flow of menstrual blood.

imperforate Sometimes applied to those gastropod (Gastropoda) shells which do not possess an umbilicus. Although the term is much used, ‘anomphalous’ or ‘non-umbilicate’ are to be preferred since an umbilicus is not a perforation.