pow·er·head / ˈpou(-ə)rˌhed/ • n. 1. inf. a powerful egomaniac: record-industry powerheads.2. any of various mechanical or electrical devices, including: ∎ a submersible pump for an aquarium that creates current within a tank. ∎ a vacuum-cleaner attachment that houses an independent motor that drives a carpet-beating rotating brush. ∎ the internal combustion engine of an outboard motor. ∎ the power unit of an automatic garage door opener.