O0078300 (ŏn′ər-əs, ō′nər-)adj.1. Troublesome or oppressive; burdensome. See Synonyms at burdensome.2. Law Entailing more liabilities than benefits or imposing significant obligations.[Middle English, from Old French onereus, from Latin onerōsus, from onus, oner-, burden.]on′er·ous·ly adv.on′er·ous·ness n.Thesaurus