1. underdrive - Adjective
2. underdrive - Verb
underdrive (not comparable)
(of a crankshaft or accessory pulley) Designed to turn at a slower speed than stock.
underdrive (third-person singular simple present underdrives, present participle underdriving, simple past underdrove, past participle underdriven)
(transitive) To slow the rate of rotation in (a pulley-based system).