The Collaborative International Dictionary of English v.0.48:

Untimely \Un*time"ly\, a.
   Not timely; done or happening at an unnatural, unusual, or
   improper time; unseasonable; premature; inopportune; as,
   untimely frosts; untimely remarks; an untimely death.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Untimely \Un*time"ly\, adv.
   Out of the natural or usual time; inopportunely; prematurely;
   unseasonably. "Let them know . . . what's untimely done."
   --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

untimely
    adv 1: too soon; in a premature manner; "I spoke prematurely"
           [syn: prematurely, untimely]
    adj 1: badly timed; "an ill-timed intervention"; "you think my
           intrusion unseasonable"; "an untimely remark"; "it was
           the wrong moment for a joke" [syn: ill-timed,
           unseasonable, untimely, wrong]
    2: uncommonly early or before the expected time; "illness led to
       his premature death"; "alcohol brought him to an untimely
       end" [syn: premature, untimely]

Moby Thesaurus II by Grady Ward, 1.0:

128 Moby Thesaurus words for "untimely":
   a bit previous, advanced, arrested, back, backward, bad,
   behindhand, belated, blocked, delayed, delayed-action, detained,
   far ahead, forward, futile, half-baked, half-cocked, hasty,
   held up, hung up, ill-adapted, ill-advised, ill-assorted,
   ill-chosen, ill-considered, ill-fitted, ill-matched, ill-seasoned,
   ill-sorted, ill-suited, ill-timed, impolitic, improper, impulsive,
   in a bind, in abeyance, inadmissible, inadvisable, inapplicable,
   inapposite, inappropriate, inapt, inauspicious, incongruous,
   inconvenient, inept, inexpedient, infelicitous, inopportune,
   intempestive, intrusive, irrelevant, jammed, late, latish,
   mal a propos, maladjusted, malapropos, misjoined, mismatched,
   mismated, misplaced, mistimed, moratory, never on time, not firm,
   obstructed, 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,
   overdue, overhasty, oversoon, precipitate, precocious, premature,
   previous, retarded, rushed, slow, soon, stopped, tardy, too early,
   too late, too soon, unadapted, unapt, unbecoming, unbefitting,
   uncrystallized, undesirable, undue, unfavorable, unfit, unfitted,
   unfitting, unfortunate, unhandy, unhappy, unjelled, unlucky,
   unmatured, unmeditated, unmeet, unpremeditated, unprepared,
   unprofitable, unpropitious, unpunctual, unqualified, unready,
   unripe, unseasonable, unseemly, unsuitable, unsuited, untoward,
   unwise, wrong