Definition of Lie and Liars:

According to the dictionary, Wikipedia and other description of words.

Lie is:

“A false statement made with deliberate intent to deceive; an intentional untruth; a falsehood.

To lie is to state something with disregard to the truth with the intention that people will accept the statement as truth.”

A Liar is:

“A liar is a person who is lying, who has previously lied, or who tends by nature to lie repeatedly—even when not necessary.”

According to the Wikipedia’s statements on lies, under psychology they have:

“The capacity to lie is noted early and nearly universally in human development. Social psychology and developmental psychology are concerned with the theory of mind, which people employ to simulate another's reaction to their story and determine if a lie will be believable. The most commonly cited milestone, what is known as Machiavellian intelligence, is at the age of about four and a half years, when children begin to be able to lie convincingly. Before this, they seem simply unable to comprehend why others don't see the same view of events that they do—and seem to assume that there is only one point of view, which is their own”.

They also have that  “Pseudologia fantastica is a term applied by psychiatrists to the behavior of habitual or compulsive lying”.
“Mythomania is the condition where there is an excessive or abnormal propensity for lying and exaggerating.^[9]”
“A recent study found that lying takes longer than telling the truth.^[10] Or, as Chief Joseph succinctly put it, "It does not require many words to speak the truth." ^[11]”