sick as a horse
Proposed by a contributor, not yet supported by evidence.
Sense 1
Sources & notes
Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).
Sense 2
Horses are said to be extremely sick at their stomachs, from being unable to relieve themselves by vomiting. Bracken, indeed, in his Farriery, gives an instance of that evacuation being procured, but by a means which he says would make the Devil vomit. Such as may have occasion to administer an emetic either to the animal or the fiend, may consult his book for the recipe.
Era: ca. 1811 (Georgian)
Sources & notes
Historical definition reproduced from Grose’s Dictionary of the Vulgar Tongue (1811 edition, public domain; Project Gutenberg #5402, retrieved 2026-07-31). Reflects the attitudes of its era.
Sense 3
a popular simile,—curious, because a horse never vomits.
một sự so sánh phổ biến, kỳ lạ vì ngựa không bao giờ nôn
Machine-translated — suggest a fix
Era: ca. 1874 (Victorian)
Sources & notes
Historical definition reproduced from Hotten’s The Slang Dictionary (1874, public domain; Project Gutenberg #42108, retrieved 2026-07-31). Reflects the attitudes of its era.
Common questions
What does “sick as a horse” mean?
Very ill.
Is “sick as a horse” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.