What is a "quasi-war?"

A "quasi-war" refers to a conflict that falls short of a full-scale war. It is a term used to describe a situation in which two or more nations engage in hostilities, but without a formal declaration of war. A quasi-war typically involves military actions, such as naval clashes or skirmishes, economic warfare, espionage, or proxy conflicts, but usually lacks the full mobilization and scale of a declared war.