The Collaborative International Dictionary of English v.0.48:

Deviate \De"vi*ate\, v. i. [imp. & p. p. Deviated; p. pr. &
   vb. n. Deviating.] [L. deviare to deviate; de + viare to
   go, travel, via way. See Viaduct.]
   To go out of the way; to turn aside from a course or a
   method; to stray or go astray; to err; to digress; to
   diverge; to vary.
   [1913 Webster]

         Thus Pegasus, a nearer way to take,
         May boldly deviate from the common track. --Pope.

   Syn: To swerve; stray; wander; digress; depart; deflect; err.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deviate \De"vi*ate\, v. t.
   To cause to deviate. [R.]
   [1913 Webster]

         To deviate a needle.                     --J. D.
                                                  Forbes.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

deviate \de"vi*ate\ (d[=e]"v[-e]*[i^]t), a.
   having behavior differing from that which is normal or
   expected, especially in an undesirable or socially
   disapproved manner; as, deviate behavior.

   Syn: deviant. [PJC]

The Collaborative International Dictionary of English v.0.48:

deviate \de"vi*ate\ (d[=e]"v[-e]*[i^]t), n.
   a person having behavior differing from that which is normal
   or socially acceptable; -- used especially to characterize
   persons whose sexual behavior is considered morally
   unacceptable.

   Syn: deviant. [PJC]

WordNet (r) 3.0 (2006):

deviate
    adj 1: markedly different from an accepted norm; "aberrant
           behavior"; "deviant ideas" [syn: aberrant, deviant,
           deviate]
    n 1: a person whose behavior deviates from what is acceptable
         especially in sexual behavior [syn: pervert, deviant,
         deviate, degenerate]
    v 1: turn aside; turn away from [syn: deviate, divert]
    2: be at variance with; be out of line with [syn: deviate,
       vary, diverge, depart] [ant: conform]
    3: cause to turn away from a previous or expected course; "The
       river was deviated to prevent flooding"

Moby Thesaurus II by Grady Ward, 1.0:

128 Moby Thesaurus words for "deviate":
   alter, ameliorate, angle, angle off, be changed, be converted into,
   be distinct, be distinguished, be in error, be mistaken,
   be renewed, be wrong, bear off, bend, bias, bottom out, branch off,
   break, bypass, change, change the bearing, checker, chop,
   chop and change, clash with, come about, come around, come round,
   conflict with, contrast with, crook, curve, deflect, degenerate,
   depart, depart from, deteriorate, detour, deviant, deviate from,
   differ, diffract, diffuse, digress, disaccord with, disagree with,
   disperse, distort, divagate, divaricate, divaricate from, diverge,
   diverge from, diversify, divert, dogleg, drift, err, excurse,
   fall into error, flop, get sidetracked, go amiss, go around,
   go astray, go awry, go round about, go wrong, hairpin, haul around,
   heel, improve, jar with, jibe, lapse, make a detour, maunder,
   meliorate, misbelieve, miscalculate, mitigate, modulate, mutate,
   not accord with, not square with, oblique, pervert, pull, ramble,
   refract, revive, scatter, serve Mammon, sex criminal, sex fiend,
   sexual deviant, sexual deviate, sexual pervert, sexual psychopath,
   sheer, shift, skew, slip, slip up, slue, stand apart,
   stand over against, stray, stumble, sway, swerve, tack,
   take a turn, trend, trip, turn, turn aside, turn away, turn into,
   turn the corner, twist, undergo a change, vary, veer, wander, warp,
   worsen, zigzag