What is the correct plural of 'octopus'?

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Have you ever said the word ‘octopuses’ and had someone tell you that the correct plural of the word is ‘octopi’? Or perhaps you’ve said ‘octopi’ and had someone tell you the correct plural is ‘octopuses’? Which one is actually correct? What plural form should you use?

In our blog post Ten Tips for Forming Plurals, number eight deals with loanwords:

8. Watch out for loanwords. Usually foreign words take on English plural endings, and in some cases it is acceptable to use either the plural from the original language or the English plural. In a few cases (usually technical terms such as ‘algae’ or ‘larvae’), the plural should always be formed following the rules of the original language. You will need to take note of which plural form to use as you come across a word. If it is acceptable to use either the original or the English plural form, make sure you are consistent – so if you are using Latin plurals, do so throughout the whole piece of work (for example, don’t swap between ‘cacti’ and ‘cactuses’).

Some loanwords have also entered the English language already in the plural form. The word spaghetti, for example, doesn’t refer to an individual strand of pasta (a spaghetto!), but the whole dish - so you don’t need to say spaghettis.

The word ‘octopus’ has existed in the English language since 1758, and when it first came into use it was given an English plural. Number three of our Ten Tips for Forming Plurals looks at how to form plurals for words ending in ‘s’:

3. If the noun ends in -ch, -s, -sh, -x, or -z, form the plural by adding -es. Click here for a word list.

Accordingly, the plural for ‘octopus’ became ‘octopuses’.

However, a grammatical movement at the time, which sought to standardise the English language, assigned many of the Latin words used in English their proper Latin plural endings. In 1818, then, ‘octopus’ was given the plural ‘octopi’.

As number eight of our Ten Tips for Forming Plurals explains, there are some words where it is acceptable to use either the English or Latin plural. So if you normally say ‘cacti’, ‘formulae’, or ‘referenda’, you should probably say ‘octopi’ -- right?

Unfortunately, the answer is no.

The plural ‘octopi’ is only correct assuming that ‘octopus’ is a Latin word, which it is not. In fact, ‘octopus’ derives from the Greek ‘oktopus’ meaning ‘eight-foot’ (‘okto’ = ‘eight’ and ‘pous’ = ‘foot’). Thus, if you wanted to form the plural using Greek language rules, the word you would use is ‘octopodes’ (pronounced: oc-top-oh-deez).

So which plural should you use – ‘octopuses’ or ‘octopodes’?

Worldwide, the accepted plural for ‘octopus’ is ‘octopuses’. In British English ‘octopodes’ is also correct – but if you choose to use it, expect some confused reactions!

Have a good week!

Sources: The Online Etymology Dictionary and Merriam-Webster

22 Mar 2016
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