The Collaborative International Dictionary of English v.0.48:

Wind-up \Wind"-up`\, n.
   Act of winding up, or closing; a concluding act or part; the
   end.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

windup
    adj 1: operated by a mechanism; "windup toys"
    n 1: a concluding action [syn: completion, culmination,
         closing, windup, mop up]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "windup":
   Z, apodosis, catastrophe, ceasing, cessation, close, coda,
   completing, completion, conclusion, consummation, crack of doom,
   culmination, curtain, curtains, death, decease, denouement,
   destination, destiny, doom, effect, end, end point, ending, envoi,
   epilogue, eschatology, expiration, fate, final solution,
   final twitch, final words, finale, finality, finis, finish,
   finishing, full development, goal, izzard, last, last breath,
   last gasp, last things, last trumpet, last words, latter end,
   maturation, maturity, omega, payoff, perfection, period,
   peroration, quietus, resolution, resting place, ripeness,
   rounding off, rounding out, stoppage, stopping place, swan song,
   term, terminal, termination, terminus, topping off