Plural of 'aircraft'

I recently came across a spelling mistake in a book that I was reading. The author referred to two aircraft as aircrafts. I knew immediately that this was wrong, but I don't know why. Can anybody tell me why the plural of aeroplane has an s but the plural of aircraft doesn't?


  • According to the OED, the first use of craft in a shipping sense was in the expression small craft meaning 'small boats in general'. A singular noun form for a plural concept.

    The earliest meaning of craft was more like 'strength' — so that too had no plural. It extended to a 'skill'-type meaning, and then to 'type of skill' — thus allowing the possibility of the plural form crafts.

    From small craft there developed the use of craft as a collective noun for boats etc. The earliest example they've found for crafts to mean 'boats' is from as recent as 1775.

    By the time heavier-than-air machines were new, craft finally existed as both a collective noun and a COUNTABLE noun. The OED quotes a newspaper comment from 1909

    What could be more concise in its definition of the complete flying-machine than the word ‘craft’, which is commonly used to signify a ship of any description.

    What seems to have happened is that people accepted the SINGULAR COUNTABLE sense and coined the word aircraft. But they also accepted the COLLECTIVE sense so that aircraft could also mean 'flying machines in general'. But they also used aircraft ro mean 'a particular collection of flying machines' — in other words a PLURAL SPECIFIC concept.

    The same word grammar extends to spacecraft — which can be used for SINGULAR, PLURAL or COLLECTIVE.

    The OED doesn't quote expression such as five craft, many craft, but this PLURAL BUT SPECIFIC seems normal to me. Certainly, the norm is five aircraft, many spacecraft etc.

    The word aeroplane was invented earlier (1855) in France (as aéroplane) for a new concept before such things actually existed. It came to mean a flying machine that worked by aerodynamic lift. As a new word for a new thing, it adopted the standard grammar for COUNTABLE nouns.

  • Thank you David for responding so quickly and explaining this so well. I thought that it might be due to it being a countable noun, but had no idea of the origin.

  • Tony, if you're interested in origins like this, see if you can read OED online. If you belong to a library that subscribes, you can can access by typing in your membership number.

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