The Collaborative International Dictionary of English v.0.48:

Aware \A*ware"\, a. [OE. iwar, AS. gew[ae]r, fr. w[ae]r wary.
   The pref. ge- orig. meant together, completely. ?. See
   Wary.]
   1. Watchful; vigilant or on one's guard against danger or
      difficulty.
      [1913 Webster]

   2. Apprised; informed; cognizant; conscious; as, he was aware
      of the enemy's designs.
      [1913 Webster]

            Aware of nothing arduous in a task
            They never undertook.                 --Cowper.
      [1913 Webster]

WordNet (r) 3.0 (2006):

aware
    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]
    2: bearing in mind; attentive to; "ever mindful of her health";
       "mindful of his responsibilities"; "mindful of these
       criticisms, I shall attempt to justify my action" [syn:
       mindful, aware] [ant: forgetful, mindless,
       unmindful]

Moby Thesaurus II by Grady Ward, 1.0:

111 Moby Thesaurus words for "aware":
   acquainted, advertent, agog, alert, alive, alive to, all ears,
   all eyes, all-knowing, apperceptive, appercipient, appreciative of,
   apprehending, apprehensive, apprised, apprised of, assiduous,
   attentive, au courant, au fait, awake, awake to, aware of, awash,
   behind the curtain, behind the scenes, brimful, brimming, careful,
   chock-full, cognizant, cognizant of, comprehending, concentrated,
   conscious, conscious of, conversant, crammed, crowded, diligent,
   earnest, enlightened, finical, finicking, finicky, heedful, hep,
   hep to, hip, impressible, impressionable, impressive, in the know,
   in the secret, informed, informed of, insightful, intelligent,
   intense, intent, intentive, jammed, knowing, knowledgeable,
   let into, loaded, meticulous, mindful, mindful of, nice, niggling,
   no stranger to, observant, observing, omniscient, on the ball,
   on the job, on to, open-eared, open-eyed, openmouthed, packed,
   perceptive, percipient, perspicacious, posted, prehensile,
   privy to, receptive, regardful, sagacious, seized of, sensible,
   sensible of, sensible to, sensile, sensitive, sensitive to,
   sentient, shrewd, streetwise, stuffed, susceptible, susceptive,
   undeceived, understanding, ware, watchful, wise, wise to,
   witting