Word Choice: Causal vs. Casual

English is full of sneaky traps for writers. The words ‘causal’ and ‘casual’, for example, contain all the same letters, mostly in the same order. This makes it easy to mix them up.

However, ‘causal’ and ‘casual’ also have completely different meanings. As such, you need to know how to use them and what the correct spellings are.

Causal (Related to Causation)

‘Causal’ (spelled with a ‘us’ in the middle) is an adjective meaning ‘related to causation’. It is used when referring to something that causes something else. For example:

There is a causal relationship between drinking beer and falling over.

This is a useful term in academic writing, where people are often interested in discovering the causes of what they’re studying (e.g. investigating the causal relationships between certain lifestyle choices and medical conditions).

Casual (Informal or Unserious)

One common meaning of ‘casual’ (spelled with ‘su’ in the middle) is ‘informal’. This is often in relation to clothing (e.g. jeans, t-shirts, trainers). For example, you might see it used like this:

You can’t go to a funeral wearing casual clothes!

More generally, something is casual if it is relaxed or unconcerned. The phrase ‘casual observer’, for instance, describes someone who isn’t looking at something closely or carefully:

To the casual observer, the building would have seemed safe.

We also refer to something that is temporary or irregular as ‘casual’, such as a ‘casual worker’ (i.e. someone who does occasional work) or ‘casual sex’ (i.e. a one-night stand).

If something is done in a casual manner, moreover, we say it was done ‘casually’:

It’s not a formal event, so feel free to dress casually.

In all cases, though, ‘casual’ indicates a relaxed or detached attitude towards something.

Causal or Casual?

These words have very distinct uses, so it’s important to look out for typos (or get your work proofread). And it’s even more vital to know the difference in the first place! Remember:

Causal = Related to causation

Casual = Informal or unserious