1. seemingly or apparently valid, likely, or acceptable; credible 2. giving a deceptive impression of truth or reliability 3. Disingenuously smooth; fast-talking
This word has always intrigued me because the first definition has a neutral, maybe even positive, connotation. But then the second and third definitions are clearly negative. So without proper context, how can someone tell if a writer or speaker intends the first meaning or the second or third? Tough one.