Ravenna grass ra·ven·nag·rass uncommon noun 1. grass often cultivated for its long white-ribbed leaves and large plumes resembling those of pampas grass SynonymsRavenna grasswool grassErianthus ravennae Related words Broader terms plume grass Parts Erianthus WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.