Added 10 October 2026 unfounded adjective Categories: Describing WordsRare Words adjective ! Definition from WordNet 3.1, Princeton University. More about unfounded at Wordnik → Where our words come from → Without a basis in reason or fact. baseless gossip Related Words: groundlessbaselessunwarrantedunsupportedidleunsubstantiatedungroundedill-foundedunjustifiedunconfirmedunreasonableunprovoked Back to today's word