Meaning & use
cog wheel
Last updated
Meaning
nouncountable
A wheel with a row of teeth around its edge that fit into the teeth of another wheel to turn it or change its speed.
Grammar: Countable: use a/an or the, and the plural cog wheels. Often used in the plural when talking about a pair or set.
Patterns
- a cog wheel turns
- cog wheels mesh
- the teeth of a cog wheel
Inside the old clock, a small cog wheel turns a larger one.
The mechanic replaced the broken cog wheel so the machine would run smoothly.
You can see the cog wheels meshing together when you open the casing.
Word forms
| plural | cog wheels |
|---|
Common combinations
- cog wheel turns
- Each cog wheel turns at a different speed.
- cog wheels mesh
- The cog wheels mesh perfectly after adjustment.
- replace a cog wheel
- He had to replace a worn cog wheel in the gearbox.
- metal cog wheel
- The toy has a metal cog wheel that drives the other parts.
Synonyms and how they differ
- gear
- Gear is the more common general word for any toothed wheel or set of wheels; cog wheel is a little more old-fashioned and specific.
- gearwheel
- Gearwheel is a technical synonym, often used in engineering; cog wheel is more everyday.
Word family
Commonly confused: cog wheel or gear?
cog wheel vs gear
A gear can be a cog wheel, but it also refers to a set of wheels or a speed setting in a vehicle. Cog wheel always means the toothed wheel itself.
Practice
The clock's mechanism stopped because a _____ was missing.
Choose one answer.
The singular 'cog wheel' is correct because 'a' comes before it. 'Cog wheels' is plural and would need 'were' instead of 'was'. 'Cog wheel's' is possessive and does not fit, and 'cog wheeling' is not a noun.
Make it your own
Write a sentence using “cog wheel”, then check it and compare it with the examples above.