noun.
The absence or closure of a normal body orifice or tubular passage such as the anus, intestine, or external ear canal.
noun.
The degeneration and resorption of one or more ovarian follicles before a state of maturity has been reached.
The Century Dictionary and Cyclopedia
noun.
The state or condition of being closed or imperforate; specifically, absence of a natural opening or passage: chiefly used in medicine and surgery.
the GNU version of the Collaborative International Dictionary of English
noun.
Absence or closure of a natural passage or channel of the body; imperforation.