The word(s) "impure" appears 4 time(s) in 4 verse(s) in Quran in Mohsin Khan translation.

(1) Say (O Muhammad صلى الله عليه وسلم): "I find not in that which has been revealed to me anything forbidden to be eaten by one who wishes to eat it, unless it be Maitah (a dead animal) or blood poured forth (by slaughtering or the like), or the flesh of swine (pork); for that surely is impure or impious (unlawful) meat (of an animal) which is slaughtered as a sacrifice for others than Allah (or has been slaughtered for idols, or on which Allah's Name has not been mentioned while slaughtering). But whosoever is forced by necessity without wilful disobedience, nor transgressing due limits; (for him) certainly, your Lord is Oft-Forgiving, Most Merciful."

(2) O you who believe (in Allah's Oneness and in His Messenger Muhammad صلى الله عليه وسلم)! Verily, the Mushrikun (polytheists, pagans, idolaters, disbelievers in the Oneness of Allah, and in the Message of Muhammad صلى الله عليه وسلم) are Najasun (impure). So let them not come near Al-Masjidal-Haram (at Makkah) after this year; and if you fear poverty, Allah will enrich you if He wills, out of His Bounty. Surely, Allah is All-Knowing, All-Wise.

(3) They will swear by Allah to you (Muslims) when you return to them, that you may turn away from them. So turn away from them. Surely, they are Rijs [i.e. Najas (impure) because of their evil deeds], and Hell is their dwelling place - a recompense for that which they used to earn.

(4) But as for him who feared standing before his Lord, and restrained himself from impure evil desires and lusts.