The definition of a liar is someone who tells lies.
An example of liar is a sixteen year old who goes out to bars with a fake id every weekend.
One that tells lies.
Origin of liar
From Middle English lier, from Old English lÄ“ogere (“liar, false witness, hypocrite"), from lÄ“ogan (“to lie, deceive, belie, betray, be in error, charge falsely"), equivalent to lie +"Ž -er. Cognate with GermanLügner (“liar"), Icelandiclygari (“liar"). More at lie.
Liar Sentence Examples
You are either a liar or very good!
"I will allow no one to call me a liar!" cried Rostov.
I was happy to leave the compulsive liar behind.
I've called him a liar and told him to his face that we couldn't be friends, but he's not backing off.
I always say that I'm basically a born liar, that writers make things up and invent things.