Is the singular or plural form of a property required when describing an object which has a count of N for that property?

For example, a two-mode or a two-modes analog filter?

  • 1
    I don't really understand your question, but your example would normally be referred to as a "two-mode analog filter". Other examples could be "five-speed gearbox", "four-horse sleigh" or "two-party system". Commented Aug 25, 2016 at 9:47
  • That's the question :) Whether you should say "five-speeds gearbox" or "five-speed gearbox", "four-horses sleigh" or "four-horse sleigh" etc.
    – Danra
    Commented Aug 25, 2016 at 10:02
  • Well then my comment has answered your question. Commented Aug 25, 2016 at 10:03
  • Indeed, you are welcome to post it as an answer.
    – Danra
    Commented Aug 25, 2016 at 10:05

2 Answers 2


John Lawler coined the Eleven-year-old boy rule which is also mentioned in another answer.

The general rule is that one-word modifiers precede the noun; modifiers of more than one word follow the noun.

Here, you are using a hyphen to make a one-word modifier ("two-mode") so it goes before the noun, as you have it. It's an adjective, describing your analogue filter.

Adjectives are never inflected for number in English.

Note that foreign adjectives in English are often inflected for number, like beaux arts — but that's not English. English adjectives (red apple/red apples) don't change. They are always expressed in a singular form.

Because adjectives are never inflected for number, the correct form is two-mode.

This question is a good, generalised question on the subject which we haven't had before. It can serve as a destination for duplicates, and we need an explicitly explanatory answer.


You would say "two-mode analog filter".

Other examples could be "five-speed gearbox", "four-horse sleigh" or "two-party system".

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