"susceptible of contraction," 1706, from French contractile, from Latin contract-, past participle stem of contrahere "to draw several objects together; draw in, shorten," from assimilated form of com "with, together" (see con-) + trahere "to draw" (see tract (n.1)). Related: Contractility.

1570s, from French sphincter, from Late Latin sphincter "contractile muscle," from Greek sphinkter "band, lace, anything that binds tight," from sphingein "to squeeze, bind," of unknown origin. First used in anatomical sense by Galen. There are several in the body; the one usually meant is the sphincter ani.