little black dress

noun3

1. •
   A simply cut and often quite short evening or cocktail dress.

   • When dressing up for a night out, let's not forget the sex appeal, allure, and slenderizing effect of ultrasheer black hosiery under that little black dress. — 2012
2. •
   (figurative) Something simple, versatile, and elegant; something that pairs well with many other things.

   • The F-bomb is the little black dress of vulgarity. Noun, verb, participle, verbal noun — it goes with everything. — 2013
3. •
   (slang) A character who is shipped with many other characters.

   • I've seen Snape/Loki. Little Black Dresses, both of them. They'll go with anybody. — 2018