The Collaborative International Dictionary of English v.0.48:

Inapt \In*apt"\, a. [Pref. in- not + apt: cf. F. inapte. Cf.
   Inept.]
   Unapt; not apt; unsuitable; inept. -- In*apt"ly, adv. --
   In*apt"ness, n.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "inapt":
   artless, awkward, bad, banal, clumsy, flat, futile, gauche,
   half-assed, ill-adapted, ill-advised, ill-assorted, ill-chosen,
   ill-considered, ill-fitted, ill-matched, ill-sorted, ill-suited,
   ill-timed, impolitic, improper, inadept, inadmissible, inadvisable,
   inapplicable, inapposite, inappropriate, inattentive, incongruous,
   inefficient, inept, inexpedient, inexpert, infelicitous,
   inopportune, insipid, irrelevant, jejune, mal a propos,
   maladjusted, maladroit, malapropos, mediocre, misjoined,
   mismatched, mismated, misplaced, out of character, out of joint,
   out of keeping, out of line, out of place, out of proportion,
   out of season, out of time, out of tune, pedestrian, poor,
   skill-less, thoughtless, unadapted, unapt, unbecoming, unbefitting,
   undeft, undesirable, undexterous, undextrous, undue, unfacile,
   unfit, unfitted, unfitting, unfortunate, unhandy, unhappy,
   unintelligent, unmeet, unproficient, unprofitable, unqualified,
   unseasonable, unseemly, unskillful, unsuitable, unsuited, untimely,
   unwise, wrong