Spelling tips

A common spelling question is when to use ‘s’ and when ‘c’ in words like this, where the ending sounds the same. In fact, I think ‘practice/practise’ is the most common example.

In UK spelling, the version with ‘c’ is the noun form, while ‘s’ is the verb form.

And when you’re writing, it’s very easy to use the wrong one.

Here’s a very handy quick tip to help you remember which one’s which: replace your word with the word 'advise' or 'advice'. Which one makes sense in the context? If it's the one that has a definite 'z' sound ('advise'), then it's the verb form you need: practise. If not, then it's the noun form: practice.

So:
Verb: Please practise this. (Please advise me about this.)
Noun: Please do your piano practice! (Please give me some advice!)

Remember that the adjective ‘practised’ derives from the verb form, so just as you would have ‘he practised hard for his speech’, you would then have ‘he is a practised speaker’ – both with ‘s’.

It gets more confusing because the US spelling is different – it uses the ‘c’ form for both noun and verb (although does also use the ‘s’ less commonly – also for both noun and verb – according to Merriam-Webster’s online dictionary).

Oddly, nouns like 'defence' and 'offence' use the 's' form in American spelling ('defense' and 'offense'). Spelling rules can never be taken for granted!
Have a look at the OED online for some example sentences and a handy usage note. Chambers' online dictionary takes a slightly different approach (and its etymology goes further back).