Each of three British soldiers is facing a court martial for alleged war crimes in Iraq. The Guardian says it is “right that [this procedure] should be used without hesitation if and when appropriate”, while the Telegraph disagrees, saying one “must not apply the standards of the more salubrious parts of Islington to the streets of Basra”.

Whichever way you look at it, one thing is shocking in its clarity: the plural of court martial turns out to be courts martial.

How has this come to be? And what is the rule, which also gives us trades union as the plural of trade union?

As far as I can tell, there is no single specialist rule. Very few web pages apparently deal with both these issues. It seems these two phrases are not united by a single rule. If anything there are two simple rules at work: be sure of what is plural, and pluralise the noun.

Both court martial and trade union are known as “compound nouns”. A court martial is a type of court. In the compound noun court martial the martial is actually an adjective — unusually at the end of the phrase — and the court is the noun. So the noun is pluralised, just as grey elephant becomes grey elephants, not *greys elephant.

As for trade union, the TUC website explains that it (the Trades Union Congress) is a single union of many trades. So that’s the TUC, but it doesn’t explain why we might use trades union as the plural.

In fact, I think that is just a misconception. Logically it’s possible to have several unions (union being the noun) so trades union makes sense. And in fact the Guardian style guide does not list trades union, though it does list several phrases in this area. It does list trades union council, but this is clearly a single council, so that’s not definitive. I’d still say Trades Union Congress is right for the specific organisation, and trade unions is right for a collection of unions.

We also have mothers-in-law and hangers-on. In both cases the noun is pluralised.

Tags: language, plurals