* Old French: "trouse" (breeches)
* Middle English: "trous" (breeches)
* Early Modern English: "trouse" (breeches), later "trouser" (singular form)
* Modern English: "trousers" (plural form)
So, the word essentially evolved from referring to a specific type of garment (breeches) to becoming the general term for pants.
Interestingly, "breeches" itself has a different root, coming from the Old Norse word "brók," meaning "breeches".
This shows how language can evolve and change over time, with words often borrowing meanings from other languages and adapting to new uses.