etiquette:  Etiquette is, almost literally, ‘just the ticket’. The primary meanings of French étiquette are ‘ticket’ and ‘label’ – and indeed it is the source of English ticket. A particular application of it in former times was to a small card which had written or printed on it directions as to how to behave properly at court – hence it came to mean ‘prescribed code of social behaviour’. => ticket
1750, from French étiquette "prescribed behavior," from Old French estiquette "label, ticket" (see ticket (n.)).
The sense development in French perhaps is from small cards written or printed with instructions for how to behave properly at court (compare Italian etichetta, Spanish etiqueta), and/or from behavior instructions written on a soldier's billet for lodgings (the main sense of the Old French word).
1. lessons for young ladies in deportment and etiquette
2. She's a real stickler for etiquette, so you'd better ask her advice.
3. The rules of etiquette are not so strict nowadays.
4. This would be against diplomatic etiquette.
5. Helen : Today's new word is etiquette – E . T . I. Q . U . E . T . T . E . – etiquette.