Interbellum

An Interbellum is a period between wars. More specifically, the term is being used for the period from 1918 to 1939, being the "interbellum" between the First and Second World Wars.

"Interbellum" can be something of a misnomer since there are usually always wars going on somewhere in the world, but generally "interbellum" contains an unspoken clause of "between wars that matter to major nations."