The word(s) "liar" appears 43 time(s) in 42 verse(s) in Quran in Mohsin Khan translation.

(31) And a believing man of Fir'aun's (Pharaoh) family, who hid his faith said: "Would you kill a man because he says: My Lord is Allah, and he has come to you with clear signs (proofs) from your Lord? And if he is a liar, upon him will be (the sin of) his lie; but if he is telling the truth, then some of that (calamity) wherewith he threatens you will befall on you." Verily, Allah guides not one who is a Musrif (a polytheist, or a murderer who shed blood without a right, or those who commit great sins, oppressor, transgressor), a liar!

(32) "The ways of the heavens, and I may look upon the Ilah (God) of Musa (Moses): But verily, I think him to be a liar." Thus it was made fair-seeming, in Fir'aun's (Pharaoh) eyes, the evil of his deeds, and he was hindered from the (Right) Path; and the plot of Fir'aun (Pharaoh) led to nothing but loss and destruction (for him).

(33) Woe to every sinful liar

(34) And surely, We shall try you till We test those who strive hard (for the Cause of Allah) and As-Sabirun (the patient), and We shall test your facts (i.e. the one who is a liar, and the one who is truthful).

(35) O you who believe! If a Fasiq (liar - evil person) comes to you with any news, verify it, lest you should harm people in ignorance, and afterwards you become regretful for what you have done.

(36) Cursed be the liars

(37) "Is it that the Reminder is sent to him [Prophet Salih عليه السلام] alone from among us? Nay, he is an insolent liar!"

(38) Tomorrow they will come to know who is the liar, the insolent one!

(39) On the Day when Allah will resurrect them all together (for their account); then they will swear to Him as they swear to you (O Muslims). And they think that they have something (to stand upon). Verily, they are liars!

(40) Have you (O Muhammad صلى الله عليه وسلم) not observed the hypocrites who say to their friends among the people of the Scripture who disbelieve: "(By Allah) If you are expelled, we (too) indeed will go out with you, and we shall never obey any one against you; and if you are attacked (in fight), we shall indeed help you." But Allah is Witness that they verily are liars.