'powerhouse' is an English compound word formed from 'power' + 'house'. 'Power' comes into English via Old French (e.g. 'povoir'/'pouvoir') ultimately from Latin roots related to 'posse' meaning 'to be able', and 'house' comes from Old English 'hūs' meaning 'dwelling'.

'powerhouse' originally appeared in English as a literal compound (often hyphenated as 'power-house') to mean a building that produces power; over time the hyphenation was dropped and the figurative sense ('a person or organization of great power/energy') developed, yielding the modern single word 'powerhouse'.

Initially it meant 'a building that produces power' (literal 'power house'); over time it acquired a figurative meaning of 'an energetic or dominant person/organization', which is now common alongside the original sense.