noun
cosh
KOSH
Cosh (noun) means a short, heavy stick or weighted tube used as a weapon to strike someone, especially over the head. Example: “The robber carried a leather cosh weighted with lead shot.”
noun
1
British A short, heavy stick or weighted tube used as a weapon to strike someone, especially over the head.
"The robber carried a leather cosh weighted with lead shot."
"Police recovered a cosh from the boot of the car."
2
mathematics The hyperbolic cosine function, written cosh x, defined as half the sum of e to the x and e to the minus x.
"A hanging chain takes the shape of a curve described by cosh."
verb
1
British To hit someone with a cosh or other heavy object.
"He was coshed from behind and left in the alley."
How to use cosh
Learner’s notesIn plain EnglishA short heavy stick used to hit someone; in maths, the hyperbolic cosine.
When to use it
The weapon sense is chiefly British and somewhat old-fashioned, common in crime writing. The maths sense is fully technical and international.
Memory tip
In maths, cosh pairs with sinh and tanh — the h stands for hyperbolic.
Trace the full origin ↓
Easily confused with
Common pairings
under the cosh
coshed over the head
leather cosh
cosh and sinh
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The robber carried a leather _____ weighted with lead shot.
Etymology
Probably comes from Romani košter (“stick”).
Related words
Rhymes for cosh
See all rhymes for cosh →Frequently asked questions
What is the difference between a cosh and a truncheon?
A truncheon is a rigid baton issued to police as standard equipment, while a cosh is typically shorter, often flexible or weighted at one end, and is associated with improvised or criminal use. In many jurisdictions carrying a cosh is an offence in itself.
How do you pronounce cosh in maths?
Most mathematicians say it as a single syllable, 'kosh', rhyming with 'posh'. Some read it aloud as 'cos-h' or 'hyperbolic cosine', particularly when clarity matters.
What does 'under the cosh' mean?
It is a British idiom meaning under heavy pressure or sustained attack, used especially in sport and business. A team defending desperately for the last twenty minutes is said to be under the cosh.
What is the meaning of cosh?
"cosh" (noun) means a short, heavy stick or weighted tube used as a weapon to strike someone, especially over the head.
