[on-er-uhs, oh-ner-]
  1. burdensome, oppressive, or troublesome; causing hardship: onerous duties.
  2. having or involving obligations or responsibilities, especially legal ones, that outweigh the advantages: an onerous agreement.

Origin of onerous

1350–1400; Middle English < Latin onerōsus, equivalent to oner- (stem of onus) burden + -ōsus -ous
Related formson·er·ous·ly, adverbon·er·ous·ness, o·ne·ros·i·ty [oh-nuh-ros-i-tee] /ˌoʊ nəˈrɒs ɪ ti/, nounnon·on·er·ous, adjectivenon·on·er·ous·ly, adverbnon·on·er·ous·ness, nounun·on·er·ous, adjectiveun·on·er·ous·ly, adverbun·on·er·ous·ness, noun

Synonyms for onerous

1. heavy, crushing, grievous; irksome, galling. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for onerosity

Historical Examples of onerosity

British Dictionary definitions for onerosity


  1. laborious or oppressive
  2. law (of a contract, lease, etc) having or involving burdens or obligations that counterbalance or outweigh the advantages
Derived Formsonerously, adverbonerousness, noun

Word Origin for onerous

C14: from Latin onerōsus burdensome, from onus load
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for onerosity



late 14c., from Old French onereus, honereus (14c., Modern French onéreux) and directly from Latin onerosus, from onus (genitive oneris) "burden" (see onus).

Online Etymology Dictionary, © 2010 Douglas Harper