de rigueur

Anything described as de rigueur is required because of etiquette, fashion, or custom. De rigueur things are expected by society. Big floppy shoes and a red nose is de rigueur for a clown.

The literal meaning of this French loan word is “in strictness,” and it has to do with strictly following etiquette and manners. It is de rigueur to put your napkin in your lap in a restaurant. It is de rigueur to send a thank-you note after receiving a gift. It doesn’t always have to be so serious, a sideways ponytail is de rigueur in an 80’s aerobics class.

Definitions of de rigueur
1

adj required by etiquette or usage or fashion

“instruction as to when and where a silk hat is de rigueur
Synonyms:
obligatory
morally or legally constraining or binding

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.