Abdominal pouch: in female Parnassiids, a sac-like ventral cavity, formed by material secreted during copulation.
Abductor: applied to muscles that open out or extend an appendage or draw it away from the body: see adductor.
Abductor mandibulae: the muscle that opens the mandibles.
Aberrant: unusual; out of the ordinary course.
Aberration: a form that departs in some striking way from the normal type; either single or occurring rarely, at irregular intervals.
Abiogenesis: spontaneous generation.
Abnormal: outside the usual range or course; not normal.
Aborted: a structure developed so as to be unfit for its normal function obsolete or atrophied.
Abraded: scraped or rubbed.
Abrupt: suddenly or without gradation.