The Collaborative International Dictionary of English v.0.48:

Impolitic \Im*pol"i*tic\, a. [Pref. im- not + politic; cf. F.
   impolitique.]
   Not politic; contrary to, or wanting in, policy; unwise;
   imprudent; indiscreet; inexpedient; as, an impolitic ruler,
   law, or measure.
   [1913 Webster]

         The most unjust and impolitic of all things, unequal
         taxation.                                --Burke.

   Syn: Indiscreet; inexpedient; undiplomatic.
        [1913 Webster]

WordNet (r) 3.0 (2006):

impolitic
    adj 1: not politic; "an impolitic approach to a sensitive issue"
           [ant: politic]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "impolitic":
   bad, botched, brash, bungled, butchered, fumbled, futile,
   ill-advised, ill-considered, ill-contrived, ill-devised, ill-done,
   ill-executed, ill-gauged, ill-judged, ill-managed, ill-suited,
   ill-timed, improper, imprudent, inadvisable, inappropriate, inapt,
   incongruous, inconsiderate, indiscreet, inept, inexpedient,
   infelicitous, injudicious, inopportune, insensate, irrational,
   mal a propos, maladroit, malapropos, mindless, misadvised,
   misconducted, misdirected, misguided, mismanaged, muffed, murdered,
   myopic, negligent, out of place, reasonless, reckless, senseless,
   shortsighted, spoiled, thoughtless, unadvised, unbefitting,
   unconsidered, undesirable, undiplomatic, undiscerning, unfit,
   unfitting, unforeseeing, unfortunate, unhappy, unmeet,
   unprofitable, unreasonable, unreflecting, unreflective,
   unseasonable, unseeing, unseemly, unsensible, unsound, unsuitable,
   untactful, unthinking, unthoughtful, untimely, unwise, witless,
   wrong