liar
n. countablen. someone who tells things that are not true. You use this word to describe a person who lies on purpose.
n. a person who tells lies or has a habit of being untruthful. While the core meaning is neutral, it is frequently used as a pejorative or an accusation.
He is a liar and cannot be trusted.
The witness was exposed as a liar when the security footage proved he was not at the scene.
In political discourse, the label of liar is often used to discredit an opponent's entire platform rather than to address specific factual inaccuracies.
Inherited from Middle English lier, liere, lyere, liȝer, lieȝer, legher, from Old English lēgere, lēogere (“liar, false witness, hypocrite”), from Proto-West Germanic leugārī, from Proto-Germanic leugārijaz (“liar”), from leuganą (“to lie”) + -ārijaz, equivalent to lie + -ar. More at lie.
Commonly used in the phrase 'a habitual liar' or 'a pathological liar'.