noun, plural o·nus·es.

a difficult or disagreeable obligation, task, burden, etc.
burden of proof.Compare onus probandi.
blame or responsibility.

Nearby words

  1. ontological argument,
  2. ontologism,
  3. ontologize,
  4. ontology,
  5. onuf's nucleus,
  6. onus probandi,
  7. onward,
  8. onwards,
  9. ony,
  10. onychalgia

Origin of onus

1630–40; < Latin: load, burden

onus probandi

[oh-noo s proh-bahn-dee; English oh-nuh s proh-ban-dahy, -dee]

noun Latin.

the burden of proof.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for onus

British Dictionary definitions for onus


noun plural onuses

a responsibility, task, or burden

Word Origin for onus

C17: from Latin: burden

onus probandi


law the Latin phrase for burden of proof
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 onus



1640s, from Latin onus "load, burden," figuratively "tax, expense; trouble, difficulty," from PIE *en-es- "burden" (cf. Sanskrit anah "cart, wagon"). Hence legal Latin onus probandi (1722), literally "burden of proving."

Online Etymology Dictionary, © 2010 Douglas Harper