Bromus bro·mus uncommon noun 1. a genus of grasses of the family Gramineae Synonymsgenus Bromus Related words Word family Bromus arvensisBromus inermisBromus japonicusBromus secalinusBromus tectorum Broader terms monocot genus Parts Gramineae Part of brome WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.