礼貌(lǐ mào) - politeness, manners; polite in Mandarin

礼貌 (lǐ mào) is politeness in the sense of good manners: the surface behaviour that shows you were brought up properly. Its usual home is 有礼貌 and 没礼貌, have manners and have none, which is how Chinese most often judges a person's conduct.

It flexes across word classes without changing shape. 很礼貌 uses it as an adjective, 礼貌地说 as an adverb with 地, and 讲礼貌 as a noun meaning to mind one's manners. All three are natural.

The trap is confusing it with 客气. 客气 is politeness performed towards a guest or a stranger, and 别客气 means do not stand on ceremony. 礼貌 is a standing quality of a person. Telling someone 别礼貌了 would mean stop having manners, which is not the friendly thing you meant.