leguminous plant le·gu·mi·nousplant uncommon noun 1. an erect or climbing bean or pea plant of the family Leguminosae Synonymslegumeleguminous plant Related words Broader terms herb Narrower terms peanutchickpeaguarsoywild pealentilhorse gramlocoweed Parts Leguminosae Part of legume WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.