Continual vs continuous – what’s the difference?

Introduction and origins

What’s the difference between continual and continuous? There’s a short answer, but it’s misleading, so – surprise! – I’m going with the long and complicated one.

Some people make a firm distinction between the two adjectives, but others don’t or only sometimes do. The distinction has merit, but it’s not categorical, more the codification of a general but lopsided pattern.

Because the words are so close in sense and use, they’re often used interchangeably (the adverbs continually and continuously even more so). This seldom leads to confusion or difficulty, but it’s also true that each word has domains it specializes in and others it’s less suited to.

Both words come from Latin continuus ‘hanging together, uninterrupted’, continual arriving via Old French continuel. Their endings, ­–al and –ous, are common adjective-forming suffixes. The words’ more recent history sheds light on their use, but first let’s look at how they’re defined, since this reflects how they’re used and gets to the centre of the problem.