Added 9 October 2026 nad noun Categories: NatureRare Words noun ! Definition from WordNet 3.1, Princeton University. More about nad at Wordnik → Where our words come from → A coenzyme present in most living cells and derived from the B vitamin nicotinic acid; serves as a reductant in various metabolic processes. Origin Clipping of gonad. From Wiktionary, via Kaikki.org (CC BY-SA) Related Words: clubdanabovejnadnanadheuraliagainstgdhaloft Back to today's word