The Collaborative International Dictionary of English v.0.48:

Completion \Com*ple"tion\, n. [L. completio a filling, a
   fulfillment.]
   1. The act or process of making complete; the getting through
      to the end; as, the completion of an undertaking, an
      education, a service.
      [1913 Webster]

            The completion of some repairs.       --Prescott.
      [1913 Webster]

   2. State of being complete; fulfillment; accomplishment;
      realization.
      [1913 Webster]

            Predictions receiving their completion in Christ.
                                                  --South.
      [1913 Webster]

WordNet (r) 3.0 (2006):

completion
    n 1: (American football) a successful forward pass in football
         [syn: completion, pass completion]
    2: a concluding action [syn: completion, culmination,
       closing, windup, mop up]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "completion":
   accomplishment, achievement, administration, bitter end,
   carrying out, catastrophe, climax, close, closure, commission,
   completing, conclusion, conduct, consummation, culmination,
   denouement, discharge, dispatch, effectuation, enactment, end,
   end result, ending, enforcement, execution, final result, finale,
   finish, finishing, fulfillment, full development, handling,
   implementation, last act, management, maturation, maturity,
   observance, payoff, perfection, performance, perpetration,
   prosecution, realization, ripeness, rounding off, rounding out,
   termination, terminus, topping off, topping-off, transaction,
   windup