The Collaborative International Dictionary of English v.0.48:

Unlovely \Un*love"ly\, a.
   Not lovely; not amiable; possessing qualities that excite
   dislike; disagreeable; displeasing; unpleasant. --
   Un*love"li*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unlovely
    adj 1: without beauty or charm [syn: unlovely,
           unpicturesque]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "unlovely":
   beautiless, blemished, blotted, cacophonic, cacophonous, defaced,
   disfigured, dysphemistic, dysphemized, homely, inelegant, marred,
   plain, short on looks, spoiled, uglified, ugly, ugly as hell,
   ugly as sin, unaesthetic, unattractive, unbeautiful, uncomely,
   unhandsome, unpleasing, unpretty, unsightly