The Collaborative International Dictionary of English v.0.48:

Unwise \Un*wise"\, a. [AS. unw[imac]s. See Un- not, and
   Wise, a.]
   Not wise; defective in wisdom; injudicious; indiscreet;
   foolish; as, an unwise man; unwise kings; unwise measures.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unwise
    adj 1: showing or resulting from lack of judgment or wisdom; "an
           unwise investor is soon impoverished"
    2: not appropriate to the purpose [syn: inexpedient, unwise]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "unwise":
   bad, brainless, childish, fatuous, foolish, futile, headless,
   ignorant, ill-advised, ill-considered, ill-contrived, ill-devised,
   ill-gauged, ill-judged, ill-suited, ill-timed, immature, impolitic,
   impractical, improper, imprudent, inadvisable, inane,
   inappropriate, inapt, incongruous, inconsiderate, indiscreet,
   inept, inexpedient, infelicitous, injudicious, inopportune,
   insensate, irrational, lackbrained, lean-minded, lean-witted,
   mal a propos, malapropos, mindless, misadvised, misguided, myopic,
   naive, not bright, of little brain, out of place, pea-brained,
   penny-wise and pound-foolish, pin-brained, reasonless, reckless,
   senseless, shortsighted, slackminded, slackwitted, thoughtless,
   unadvised, unbefitting, unconsidered, undesirable, undiscerning,
   unfit, unfitting, unforeseeing, unfortunate, ungifted, unhappy,
   unintellectual, unintelligent, unmeet, unprofitable, unreasonable,
   unreasoning, unreflecting, unreflective, unseasonable, unseeing,
   unseemly, unsensible, unsound, unsuitable, untalented, unthinking,
   unthoughtful, untimely, witless, wrong