et ‧ i ‧ quette /ˈetɪket $ -kət/ BrE AmE noun [uncountable]
[ Date: 1700-1800 ; Language: French ; Origin: étiquette 'ticket' ( ⇨ ↑ ticket 1 ); perhaps because rules of behavior were written on a small card, like a ticket ]
the formal rules for polite behaviour in society or in a particular group:
strict rules of professional etiquette