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

(11) He [Yusuf (Joseph)] said: "It was she that sought to seduce me;" and a witness of her household bore witness (saying): "If it be that his shirt is torn from the front, then her tale is true and he is a liar!

(12) They [Yusuf's (Joseph) men] said: "What then shall be the penalty of him, if you are (proved to be) liars."

(13) In order that He may make manifest to them the truth of that wherein they differ, and that those who disbelieved (in Resurrection, and in the Oneness of Allah) may know that they were liars.

(14) And when those who associated partners with Allah see their (Allah's so-called) partners, they will say: "Our Lord! These are our partners whom we used to invoke besides you." But they will throw back their word at them (and say): "Surely! You indeed are liars!"

(15) And when We change a Verse (of the Qur'an,) in place of another - and Allah knows best what He sends down - they (the disbelievers) say: "You (O Muhammad صلى الله عليه و سلم) are but a Muftari! (forger, liar)." Nay, but most of them know not.

(16) It is only those who believe not in the Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) of Allah, who fabricate falsehood, and it is they who are liars.

(17) Nay, but We have brought them the truth (Islamic Monotheism), and verily, they (disbelievers) are liars.

(18) And those who accuse chaste women, and produce not four witnesses, flog them with eighty stripes, and reject their testimony forever. They indeed are the Fasiqun (liars, rebellious, disobedient to Allah).

(19) Why did they not produce four witnesses? Since they (the slanderers) have not produced witnesses! Then with Allah they are the liars.

(20) "You are but a human being like us and verily, we think that you are one of the liars!