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Synonyms

onerous

American  
[on-er-uhs, oh-ner-] / ˈɒn ər əs, ˈoʊ nər- /

adjective

  1. burdensome, oppressive, or troublesome; causing hardship.

    onerous duties.

    Synonyms:
    galling, irksome, grievous, heavy
  2. having or involving obligations or responsibilities, especially legal ones, that outweigh the advantages.

    an onerous agreement.


onerous British  
/ ˈəʊ-, ˈɒnərəs /

adjective

  1. laborious or oppressive

  2. law (of a contract, lease, etc) having or involving burdens or obligations that counterbalance or outweigh the advantages

"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

Other Word Forms

Etymology

Origin of onerous

1350–1400; Middle English < Latin onerōsus, equivalent to oner- (stem of onus ) burden + -ōsus -ous

Explanation

If one teacher gives you three hours of homework a night, that's rough. But if all of your teachers do it, that makes the task of completing your homework an onerous one, to say the least. If something is onerous, it is very difficult to deal with or do. A near synonym is burdensome. In legal usage, onerous describes a contract or lease that has more obligations than advantages. Onerous derives from Middle English, from Old French onereus, from Latin onerōsus, from onus "burden." In English, an onus is a task or duty that is onerous, or very difficult.

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Vocabulary lists containing onerous

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

The measures are aimed at making both listing and staying listed in London cheaper and less onerous.

From The Wall Street Journal Aug. 10, 2026

Personally, I found probate less onerous than settling her estate without a will.

From MarketWatch Jul. 29, 2026

Falling numbers of workers spell yet another challenge for Europe's struggling top economy, already battling onerous red tape, high energy costs and fierce competition in its traditional industries.

From Barron's Jun. 15, 2026

As one of Jamaica's largest buyers of the fruit, for Gray's Pepper the shortages have been onerous.

From BBC May 31, 2026

This apparatus displayed Rutherford’s hallmark simplicity and style, but the procedure was unspeakably onerous.

From "Big Science" by Michael Hiltzik

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