The Collaborative International Dictionary of English v.0.48:

Cognizant \Cog"ni*zant\ (? or ?), a. [See Cognizance, and cf.
   Connusant.]
   Having cognizance or knowledge. (of).
   [1913 Webster]

WordNet (r) 3.0 (2006):

cognizant
    adj 1: (sometimes followed by `of') having or showing knowledge
           or understanding or realization or perception; "was aware
           of his opponent's hostility"; "became aware of her
           surroundings"; "aware that he had exceeded the speed
           limit" [syn: aware(p), cognizant, cognisant] [ant:
           incognizant, unaware]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "cognizant":
   acknowledging, alive, alive to, all-knowing, apperceptive,
   appercipient, appreciative, appreciative of, apprehending,
   apprehensive, apprised of, au courant, awake, awake to, aware,
   aware of, behind the curtain, behind the scenes, beholden,
   cognizant of, comprehending, conscious, conscious of, crediting,
   grateful, hep to, impressible, impressionable, impressive,
   in the know, in the secret, indebted to, informed of, insightful,
   intelligent, knowing, knowledgeable, let into, mindful, mindful of,
   much obliged, no stranger to, obliged, omniscient, on to,
   perceptive, percipient, perspicacious, prehensile, privy to,
   receptive, sagacious, seized of, sensible, sensible of,
   sensible to, sensile, sensitive to, sentient, shrewd, streetwise,
   susceptible, susceptive, thankful, undeceived, under obligation,
   understanding, wise, wise to, witting