clinch·er \ˈklinchə(r)\noun (-s) : one that clinches: as a.: a decisive fact, argument, act, or remark < the expense was the clincher that persuaded us to give up the enterprise > b.: a machine in commercial canning for positioning a lid loosely on the can prior to sealing it c.orclincher tire: an automobile tire with flanged beads fitting into the wheel rim