means A dusty yellowish-brown color, and the sturdy fabric of that color long associated with military uniforms and rugged trousers.

from From Urdu and Persian khākī, meaning 'dust-colored,' from khāk, 'dust' or 'soil.' British soldiers in 19th-century India swapped their conspicuous red coats for this earth-toned cloth that vanished into the dusty landscape — and the word, like the color, marched home with the empire.