The Collaborative International Dictionary of English v.0.48:

Suspect \Sus*pect"\, a. [L. suspectus, p. p. of suspicere to
   look up, admire, esteem, to look at secretly or askance, to
   mistrust; sub under + specere to look: cf. F. suspect
   suspected, suspicious. See Spy, and cf. Suspicion.]
   1. Suspicious; inspiring distrust. [Obs.]
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            Suspect [was] his face, suspect his word also.
                                                  --Chaucer.
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   2. Suspected; distrusted. [Obs.]
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            What I can do or offer is suspect.    --Milton.
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The Collaborative International Dictionary of English v.0.48:

Suspect \Sus*pect"\, v. i.
   To imagine guilt; to have a suspicion or suspicions; to be
   suspicious.
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         If I suspect without cause, why then make sport at me.
                                                  --Shak.
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The Collaborative International Dictionary of English v.0.48:

Suspect \Sus*pect"\, n. [LL. suspectus. See Suspect, a.]
   1. Suspicion. [Obs.] --Chaucer.
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            So with suspect, with fear and grief, dismayed.
                                                  --Fairfax.
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   2. One who, or that which, is suspected; an object of
      suspicion; -- formerly applied to persons and things; now,
      only to persons suspected of crime. --Bacon.
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The Collaborative International Dictionary of English v.0.48:

Suspect \Sus*pect"\, v. t. [imp. & p. p. Suspected; p. pr. &
   vb. n. Suspecting.]
   1. To imagine to exist; to have a slight or vague opinion of
      the existence of, without proof, and often upon weak
      evidence or no evidence; to mistrust; to surmise; --
      commonly used regarding something unfavorable, hurtful, or
      wrong; as, to suspect the presence of disease.
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            Nothing makes a man suspect much, more than to know
            little; and therefore men should remedy suspicion by
            procuring to know more.               --Bacon.
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            From her hand I could suspect no ill. --Milton.
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   2. To imagine to be guilty, upon slight evidence, or without
      proof; as, to suspect one of equivocation.
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   3. To hold to be uncertain; to doubt; to mistrust; to
      distruct; as, to suspect the truth of a story. --Addison.
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   4. To look up to; to respect. [Obs.]
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   Syn: To mistrust; distrust; surmise; doubt.
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WordNet (r) 3.0 (2006):

suspect
    adj 1: not as expected; "there was something fishy about the
           accident"; "up to some funny business"; "some definitely
           queer goings-on"; "a shady deal"; "her motives were
           suspect"; "suspicious behavior" [syn: fishy, funny,
           shady, suspect, suspicious]
    n 1: someone who is under suspicion
    2: a person or institution against whom an action is brought in
       a court of law; the person being sued or accused [syn:
       defendant, suspect] [ant: complainant, plaintiff]
    v 1: imagine to be the case or true or probable; "I suspect he
         is a fugitive"; "I surmised that the butler did it" [syn:
         suspect, surmise]
    2: regard as untrustworthy; regard with suspicion; have no faith
       or confidence in [syn: distrust, mistrust, suspect]
       [ant: bank, rely, swear, trust]
    3: hold in suspicion; believe to be guilty; "The U.S. suspected
       Bin Laden as the mastermind behind the terrorist attacks"

Moby Thesaurus II by Grady Ward, 1.0:

166 Moby Thesaurus words for "suspect":
   a bit thick, a bit thin, absurd, account as, accused, arguable,
   assume, at issue, awake a doubt, be afraid, be diffident,
   be doubtful, be dubious, be possessive, be skeptical, be uncertain,
   believe, beyond belief, call in question, challenge, conceive,
   conclude, confutable, conjectural, consider, contest, contestable,
   contested, controversial, controvertible, correspondent, daresay,
   debatable, deduce, deem, defendant, deniable, disbelieve,
   disbelieved, discredited, disputable, dispute, disputed, distrust,
   divine, doubt, doubtable, doubted, doubtful, dream, dubious,
   dubitable, esteem, estimate, expect, exploded, fancy, feel, gather,
   grant, greet with skepticism, guess, half believe,
   harbor suspicions, hard of belief, hard to believe, have a feeling,
   have a hunch, have an idea, have an impression, have an inkling,
   have reservations, have the idea, hold, hold as, iffy, imagine,
   implausible, in dispute, in doubt, in dubio, in question,
   inconceivable, incredible, infer, judge, let, let be, libelee,
   look upon as, maintain, misdoubt, misgive, mistakable, mistrust,
   mistrusted, moot, not deserving belief, open, open to doubt,
   open to question, open to suspicion, opine, passing belief,
   prefigure, preposterous, presume, presuppose, presurmise, prisoner,
   problematic, provisionally accept, query, question, questionable,
   questioned, raise a question, reckon, refutable, regard, repute,
   respondent, ridiculous, say, scruple, sense, set down as, shadowy,
   shady, shaky, smell a rat, speculative, staggering belief, suppose,
   suppositional, surmise, suspected, suspicion, suspicious, take,
   take for, take for granted, take it, take to be, tall, theorize,
   thick, thin, think, throw doubt upon, treat with reserve, trow,
   unbelievable, uncertain, unclear, unconvincing, under a cloud,
   under suspicion, understand, unearthly, ungodly, unimaginable,
   unthinkable, unworthy of belief, view as, ween