The Collaborative International Dictionary of English v.0.48:
Smooth-spoken \Smooth"-spo`ken\, a. Speaking smoothly; plausible; flattering; smooth-tongued. [1913 Webster]WordNet (r) 3.0 (2006):
smooth-spoken adj 1: expressing yourself readily, clearly, effectively; "able to dazzle with his facile tongue"; "silver speech" [syn: eloquent, facile, fluent, silver, silver- tongued, smooth-spoken]