English is easy when it comes to plurals. Only the noun changes when we form the plural – adjectives and other modifiers stay the same: Red rose, red roses. Stone house, stone houses.

That rule doesn’t change when the modifier comes after the noun – as in court-martial, notary public, attorney general or mother-in-law. Pluralize only the noun: courts-martial, notaries public, attorneys general, mothers-in-law.

When in doubt, ask yourself which word in the phrase does not make sense as a noun, and pluralize the other one. (Yes, “general” can be a noun, but an attorney general is not an officer in the Army. “In-law” can be a noun, but it’s usually plural when used alone – “I love my in-laws.”)