Definition of "opponens" [opponens]

• In anatomy, an opponent muscle of the hand or foot of man and some anthropoid apes, lying on the inner or outer side of the hand or foot. (noun)

The Century Dictionary (Public Domain)

• "One of the most important of these motions is that of the thumb as placed in opposition to the fingers, and effected by a muscle termed opponens pollicis."
• "The same is the case with the apes, except that the Orang-utan has a small "opponens" attached to the great toe."
• "An "opponens" muscle is one which passes from the bones of the wrist to one or other of the bones of the middle of the hand called metacarpals, and the opponens pollicis passes of course, as its name implies, to the metacarpal of the pollex or thumb."