The Collaborative International Dictionary of English v.0.48:

Uninvited \Uninvited\
   See invited.

WordNet (r) 3.0 (2006):

uninvited
    adj 1: unwelcome and unwanted; "uninvited guests"; "uninvited
           thoughts"

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "uninvited":
   arbitrary, autonomous, discretional, discretionary, elective, free,
   free will, gratuitous, independent, nonmandatory, offered,
   optional, proffered, self-acting, self-active, self-determined,
   self-determining, spontaneous, unacceptable, unagreeable, unasked,
   unasked-for, unbesought, unbidden, uncalled-for, uncoerced,
   uncompelled, undesirable, undesired, unforced, uninfluenced,
   unpressured, unprompted, unrequested, unrequired, unsolicited,
   unsought, unwanted, unwelcome, unwished, voluntary, volunteer,
   willful