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