Added 9 October 2026 fuel-efficient adjective Categories: Obscure Words adjective ! Definition from The American Heritage® Dictionary of the English Language, 5th Edition., via Wordnik. More about fuel-efficient at Wordnik → Where our words come from → Operable using less fuel than others of the same kind. from The American Heritage® Dictionary of the English Language, 5th Edition. via Wordnik Related Words: eco-friendlyecologicaleconomiceconomicalefficientenergy-efficientenergy-savingfrugalfuellow-powerthriftytight Back to today's word