onerous (oh-n<<schwa>>r-<<schwa>>s oron-<<schwa>>r-<<schwa>>s), adj.1. Excessively burdensome or troublesome; causing hardship <onerous discovery requests>.2. Having or involving obligations that outweigh the advantages < onerous property>.3.Civil law. Done or given in return for something of equivalent value; supported by consideration <an onerous contract>. Cf. GRATUITOUS(1). — onerousness,n.

[Blacks Law 8th]