Added 9 October 2026 energy-efficient adjective Categories: Obscure Words adjective ! Definition from Wiktionary (CC BY-SA). More about energy-efficient at Wordnik → Where our words come from → That does not consume a lot of energy. Related Words: eco-friendlyecologicaleconomicaleffectiveefficiencyefficientenergyenergy-savingfrugalfuel-efficientgas-guzzlinglow-power Back to today's word