Literally, French for "outside of the work". "L'oeuvre" is work in the sense of a work of art, or a work of literature. The concept here is that the "work" is the main part of the meal, the chef's artistic creation. The "hors d'oeuvre" is the appetizer, coming before the main course; it is outside of the work.
Fascinating how much a language can imply about a culture, isn't it?