Entry 2 senses · 2 variants Webster, 1913 Sinch · IPA n. v. t. 01 n. A saddle girth made of leather, canvas, woven horsehair, or woven grass. 1. A saddle girth made of leather, canvas, woven horsehair, or woven grass.[Western U.S.] 02 v. t. To gird with a sinch; to tighten the sinch or girth of (a saddle); as, to sinch up a sadle. 1. To gird with a sinch; to tighten the sinch or girth of (a saddle); as, to sinch up a sadle.[Western U.S.]