blue jeans

noun (used with a plural verb)

close-fitting trousers made of blue denim or denimlike fabric, having pockets and seams often reinforced with rivets, and worn originally as work pants but now also as casual attire by persons of all ages.Compare jean(def 2), Levi's.

Origin of blue jeans

First recorded in 1850–55

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

They had on windbreakers the color of old cement and blue-jeans, with their waistbands concealed.
Little Brother
Cory Doctorow
But even in defeat, he carried down with him between rigid jaws the blue-jeans banner of victory.
Heart of the Blue Ridge
Waldron Baily

from 1843 as a type of fabric; see jean. As short for blue jeans trousers, from 1878.