cotter pin: meaning, definition, pronunciation and examples
C1Technical/Industrial, Informal
Quick answer
What does “cotter pin” mean?
A split or wedge-shaped pin inserted through a hole to secure or fasten mechanical parts, especially by spreading its ends.
Audio
Pronunciation
Definition
Meaning and Definition
A split or wedge-shaped pin inserted through a hole to secure or fasten mechanical parts, especially by spreading its ends.
A simple, low-cost fastener with a split design that allows one end to be bent or spread after insertion to prevent removal, commonly used in machinery, bicycles, and automotive assemblies.
Dialectal Variation
British vs American Usage
Differences
The term is used identically in both varieties to describe the same mechanical component. No significant lexical or design differences.
Connotations
Neutral technical term in both regions. May connote simple, robust, low-tech fastening solutions.
Frequency
Equally common in technical/engineering contexts in both the UK and US. Very rare in general non-technical discourse.
Grammar
How to Use “cotter pin” in a Sentence
[Verb] + the + cotter pin + [Prepositional Phrase] (e.g., 'Insert the cotter pin through the clevis.')The + [Noun] + is + [Past Participle] + with + a + cotter pin (e.g., 'The linkage is secured with a cotter pin.')Vocabulary
Collocations
Examples
Examples of “cotter pin” in a Sentence
verb
British English
- We need to cotter the pin in place properly.
- He cottered the linkage to prevent it from sliding.
American English
- Make sure you cotter that pin before operating.
- The mechanic cottered the castle nut.
adjective
British English
- The cotter-pin assembly failed.
- Use a cotter-pin lock for safety.
American English
- Check the cotter pin connection.
- It's a cotter-pin style fastener.
Usage
Meaning in Context
Business
Virtually never used.
Academic
Used in engineering, mechanics, and materials science textbooks and papers.
Everyday
Rare, except when discussing DIY repairs on bicycles, lawnmowers, or trailers.
Technical
The primary register. Common in mechanical engineering, automotive repair, aviation maintenance, and industrial assembly manuals.
Watch out
Common Mistakes When Using “cotter pin”
- Confusing it with a 'clevis pin' (the pin that the cotter pin often secures).
- Using 'cotter pin' to refer to any kind of pin or bolt.
- Misspelling as 'coter pin' or 'cotterpin' (should be two words or hyphenated).
FAQ
Frequently Asked Questions
Typically, no. Once the ends are bent (splayed) to secure it, straightening them weakens the metal. It's considered a single-use fastener for safety-critical applications.
They are generally synonymous. However, 'split pin' is a broader term, while 'cotter pin' sometimes specifically refers to a pin used with a 'cotter' (wedge) or in a 'cottered' joint, like old bicycle crank arms.
In a temporary, non-critical, low-stress situation, it might work, but it is highly discouraged. Paperclips lack the strength, corrosion resistance, and designed mechanical properties of a proper cotter pin and are a safety hazard in machinery.
They are ubiquitous in automotive steering linkages, aircraft control systems, agricultural equipment, bicycle assemblies (especially older models), and anywhere a simple, reliable, and visually verifiable locking mechanism is needed.
A split or wedge-shaped pin inserted through a hole to secure or fasten mechanical parts, especially by spreading its ends.
Cotter pin is usually technical/industrial, informal in register.
Cotter pin: in British English it is pronounced /ˈkɒtə pɪn/, and in American English it is pronounced /ˈkɑːtər pɪn/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Think: 'COTTER pin' = 'COTTAGE' repair. It's a simple, rustic-looking pin with split ends, like a basic fastener you might use in a cottage workshop.
Conceptual Metaphor
A MECHANICAL LOCK; A SIMPLE SAFETY DEVICE.
Practice
Quiz
What is the primary function of a cotter pin?