Liar
1. someone who represents one set of facts, while knowing that a
different set of facts prevails;
2. (popular) someone who having led others to believe one thing, does
a different thing; a promise-breaker;
3. (colloquial) someone whose general conduct, level of
reliability,
relationship with truth, and past
preformance leave him or her with
little to no credibility in peoples' opinion;