The Collaborative International Dictionary of English v.0.48:

Unprofitable \Unprofitable\
   See profitable.

WordNet (r) 3.0 (2006):

unprofitable
    adj 1: producing little or no profit or gain; "deposits
           abandoned by mining companies as unprofitable" [ant:
           profitable]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "unprofitable":
   abortive, barren, bootless, deleterious, detrimental,
   disadvantageous, disserviceable, fruitless, futile, gainless,
   harmful, ineffective, inefficient, injurious, losing,
   nonremunerative, otiose, pointless, prejudicial, profitless,
   purposeless, rewardless, sterile, unadvantageous, unavailing,
   unfavorable, unfruitful, unproductive, unremunerative, unrewarding,
   useless, worthless