Con`trac*til"i*ty (?), n. 1. The quality or property by which bodies shrink or contract.

2. (Physiol.) The power possessed by the fibers of living muscle of contracting or shortening.

&fist; When subject to the will, as in the muscles of locomotion, such power is called voluntary contractility; when not controlled by the will, as in the muscles of the heart, it is involuntary contractility.