D defs.my
Entry 2 senses Webster, 1913

Clincher

/klĭn'-chẽr/ · Clinch·er · IPA /klˈɪntʃər/
01 n. One who, or that which, clinches; that which holds fast.
  1. 1.
    One who, or that which, clinches; that which holds fast.
  2. 2.
    That which ends a dispute or controversy; a decisive argument.