capper

1 the last part of a process or action <the capper to the campaign rally was an appearance by the candidate himself> Synonyms finale, close, closing, conclusion, consummation, end, endgame, ending, finis, finish, grand finale, home stretch, mop-up, windup, wrap-upRelated Words acme, apex, capstone, climax, copestone, coup de grâce (or coup de grace), crescendo, crown, culmination, high-water mark, meridian, peak, pinnacle, summit, tip-top, top, zenith; aftermath, anticlimax, coda, epilogue (also epilog), postscript; shank, tag end, tail endNear Antonyms foreword, introduction, overture, preamble, preface, prelude, prologue (also prolog)Antonyms baseline, beginning, dawn, day one, nascence, nascency, opening, start

2 something (as a fact or argument) that is decisive or overwhelming <she was smart, she was pretty, but here's the capper—she was kind, unlike the other girls> Synonyms clincher, coup de grâce (or coup de grace), crusher, topperRelated Words confutation, deathblow, knockout; determinant, factor