A brownish cloth or color, often associated with uniforms.
A uniform color named for dust
Persian
khāk
‘Dust’
into Hindi / Urdu: the dust noun supplies a color description in Hindi and Urdu.
Hindi / Urdu
khākī
‘Dust-colored’
into English: english uses the borrowed color word for fabric and its shade; Hindi and Urdu are parallel inputs.
English
khaki
‘A brownish cloth or color’
Hindi and Urdu khākī mean dust-colored, built on khāk, dust, from Persian. English borrowed the color and fabric word.
Hindi and Urdu are parallel inputs, not successive borrowing stages.
The Hindi and Urdu source adjective means dust-colored, built on a dust word from Persian.
The military association is familiar, but the older adjective describes dust.