onion plant onionp·lant uncommon noun 1. bulbous plant having hollow leaves cultivated worldwide for its rounded edible bulb Synonymsoniononion plantAllium cepa Related words Broader terms alliaceous plant Narrower terms shallottree onionWelsh onionred-skinned onion Part of onionisothiocyanate WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
