Source : Webster's Revised Unabridged Dictionary (1913)

Unscrupulous \Un*scru"pu*lous\, a.
   Not scrupulous; unprincipled. -- {Un*scru"pu*lous*ly}, adv.
   -- {Un*scru"pu*lous*ness}, n.

Source : WordNet®

unscrupulous
     adj 1: without scruples or principles; "unscrupulous politicos who
            would be happy to sell...their country in order to
            gain power" [ant: {scrupulous}]
     2: lacking honesty and oblivious to what is honorable [syn: {dishonest}]