competitor, n. [rival], contestant, [opponent], [antagonist].
complain, v. [murmur], [repine], [grumble], [whine], [croak].
complaining, a. [murmuring], repining, querimonious, [querulous], [discontented], grumbling.
complaint, n. [murmur], [plaint], [lamentation]; [malady], [ailment], [disease]; [accusation], allegation, [information].
complete, v. [finish], [consummate], [perfect].
complete, a. [entire], [consummate], [whole], integral, plenary, unabridged, intact.
completion, n. [consummation], integration, elaboration, finishing, [realization], effectuation.
complex, a. composite, [compound], [mixed]; [complicated], [intricate], involved. Antonyms: incomplex, [simple], [obvious].
complexity, n. [intricacy], [entanglement], [complication].
compliance, n. [yielding], concession, [submission], [obedience], acquiescence.