The name of Pugo has its origin from Pangasinan, a language used in Pangasinan, a province south of La Union. Pugo as well as other parts of southern La Union was once part of the ethno-linguistic territory of Pangasinan-speaking people prior to political subdivision during the Spanish regime. Now, only a minority speaks Pangasinan in La Union mainly in the towns of Rosario and Santo Tomas. The term "Pugo" means "islet"; while Pugo itself is not an island, the term describes the huge rock beds in the Tapuacan River. The river also features rock walls and huge rocks which are now known as the Tapuakan Resort in Barangay Cares.