Merriam-Webster Collegiate Dictionary - cinch

 I. noun  Etymology: Spanish ~a, from Latin cingula girdle, girth, from cingere — more at cincture  Date: 1859  1. a girth for a pack or saddle  2. a tight grip  3.  a. a thing done with ease  b. a certainty to happen it's a ~ he'll break the record  II. verb  Date: 1866  transitive verb  1.  a. to put a ~ on  b. to fasten (as a belt or strap) tightly  2. to make certain ; assure the goal that ~ed the victory  intransitive verb to tighten the ~ — often used with up