The Collaborative International Dictionary of English v.0.48:
Conscienceless \Con"science*less\, a. Without conscience; indifferent to conscience; unscrupulous. [1913 Webster] Conscienceless and wicked patrons. --Hookre. [1913 Webster]WordNet (r) 3.0 (2006):
conscienceless adj 1: lacking a conscience; "a conscienceless villain"; "brash, unprincipled, and conscienceless"; "an unconscionable liar" [syn: conscienceless, unconscionable]