The Collaborative International Dictionary of English v.0.48:

Unbefitting \Unbefitting\
   See befitting.

WordNet (r) 3.0 (2006):

unbefitting
    adj 1: not befitting; "behavior unbefitting a father"

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "unbefitting":
   bad, futile, ill-adapted, ill-advised, ill-assorted, ill-chosen,
   ill-considered, ill-fitted, ill-matched, ill-seasoned, ill-sorted,
   ill-suited, ill-timed, impolitic, improper, inadmissible,
   inadvisable, inapplicable, inapposite, inappropriate, inapt,
   inauspicious, incongruous, inconvenient, inept, inexpedient,
   infelicitous, inopportune, intempestive, intrusive, irrelevant,
   late, mal a propos, maladjusted, malapropos, misjoined, mismatched,
   mismated, misplaced, mistimed, off base, out of character,
   out of joint, out of keeping, out of line, out of phase,
   out of place, out of proportion, out of season, out of time,
   out of tune, premature, too late, too soon, unadapted, unapt,
   unbecoming, uncomely, undesirable, undue, unfavorable, unfit,
   unfitted, unfitting, unfortunate, unhandy, unhappy, unlucky,
   unmeet, unprofitable, unpropitious, unqualified, unready, unripe,
   unseasonable, unseemly, unsuitable, unsuited, untimely, untoward,
   unwise, wrong