Word list: C

cash flow

Two words.


21st century


One word.


One word.

client side, client-side

Two words as a noun, hyphenated as an adjective: client-side validation; validation on the client side.

CO2 (carbon dioxide)

The 2 of CO2 is subscripted.



compare with, compare to

A useful distinction can be served by writing compare to to mean liken, and compare with to mean contrast:

  • Shall I compare thee to a summer’s day?
  • … compared with the same period last year.

compass points

north, northeast, east, southeast, south, southwest, west, northwest

Not hyphenated. Not capitalised except where the word forms part of the name of a country, administrative region, or geopolitical entity, e.g. North America, West Midlands.

So you’d write, “It’s colder in the northeast than in the southwest.”

When it comes to compounds consisting of three points, hyphenate as follows: south-southeast, north-northwest, etc.

complement, compliment

Commonly confused. Complement means go together; compliment means praise.

complementary, complimentary

Like complement and compliment (above), these words are sometimes confused.

  • Complementary means combining in such a way as to enhance or emphasise the qualities of each other or another. “The players in the team have complementary skills.”
  • Complimentary means praising or approving. It can also mean free of charge.


“Comprised of” is widely regarded as incorrect and is best avoided. You can say any of the following:

  • The group comprises subject-matter experts.
  • The group consists of subject-matter experts.
  • The group is composed of subject-matter experts.
  • The group is made up of subject-matter experts.

But not “comprised of”.

continual, continuous

  • A continual event is one that occurs repeatedly, over and over.
  • A continuous event goes on incessantly, non-stop.

If it rained continually throughout your holiday, you might think it rather bad luck. If it rained continuously throughout your holiday, that really would be rotten luck and probably a freak meteorological event.

The noise of vehicles on a busy road might be continual: one swoosh after another. On a motorway, vehicle noise is more likely to be continuous: a constant thrum.

Many readers won’t make the distinction, so you might want to use another word such as “recurring” for continual or “incessant” for continuous.

cooperate, cooperation

Not hyphenated.

coordinate, coordination

Not hyphenated.

COP26, COP27, COP28, etc.

Block caps, no space.


One word.


One word.


One word, no initial cap.

Covid, Covid-19

Initial cap. No need to write -19 at the end unless making a distinction.


One criterion; two or more criteria.


One word, no hyphen.