The Collaborative International Dictionary of English v.0.48:

Unchecked \Unchecked\
   See checked.

WordNet (r) 3.0 (2006):

unchecked
    adj 1: not restrained or controlled; "unbridled rage"; "an
           unchecked temper"; "ungoverned rage" [syn: unbridled,
           unchecked, uncurbed, ungoverned]

Moby Thesaurus II by Grady Ward, 1.0:

136 Moby Thesaurus words for "unchecked":
   abandoned, abiding, apocryphal, artless, bluff, blunt, broad,
   brusque, candid, changeless, constant, continuing, direct,
   disobedient, downright, durable, enduring, explicit, firm, fixed,
   forthright, frank, frankhearted, free, free-speaking, free-spoken,
   free-tongued, frozen, genuine, go-go, headstrong, heady,
   heart-to-heart, immobile, immoderate, immutable, incontinent,
   indulgent, ingenuous, insubordinate, intact, intemperate,
   inviolate, irrepressible, irresponsible, lasting, lawless, lax,
   licentious, loose, mutinous, nonofficial, nonrestrictive, open,
   openhearted, out of control, out of hand, outspoken, permanent,
   permissive, perpetual, persistent, plain, plain-spoken, quiescent,
   rampant, reinless, remaining, rigid, riotous, round, self-willed,
   sincere, solid, stable, static, stationary, staying, steadfast,
   straight, straight-out, straightforward, sustained, torpid,
   transparent, unaccountable, unaltered, unattested, unauthentic,
   unauthenticated, unauthoritative, unbridled, uncertified,
   unchangeable, unchanged, unchanging, uncoerced, uncompelled,
   unconfirmed, unconstrained, uncontrolled, uncorroborated, uncurbed,
   undemonstrated, undestroyed, undisciplined, unequivocal, unfading,
   unfailing, unforced, ungoverned, unguarded, uninhibited,
   unmastered, unmeasured, unmuzzled, unofficial, unproved, unreined,
   unrepressed, unreserved, unrestrained, unrestrictive, unruly,
   unshifting, unsubdued, unsuppressed, unvalidated, unvaried,
   unvarying, unverified, unwarranted, wanton, wild, wildcat,
   willful