comme il faut Look up comme il faut at Dictionary.com
1756, French, literally "as it should be;" from comme "as, like, how," from Old French com, from Vulgar Latin quomo, from Latin quomodo "how? in what way?," pronominal adverb of manner, related to quam "how much?," qui "who" (from PIE root *kwo-, stem of relative and interrogative pronouns).