[babak_ap]

The article isn't wrong, it's just incomplete.

"Khaki is a loanword from Hindustani (Urdu or Hindi) ख़ाकी/خاکی 'soil-colored', which in turn comes from Persian خاک [xɒːk] khâk 'soil' + ی- (adjectival ending); it came into English via the British Indian Army."

Source: https://en.wikipedia.org/wiki/Khaki

[kranner]

Hindi/Urdu native speaker here: "khaak" means dust, not soil exactly. I believe it is the same in Farsi as well. "Khaaki" would mean 'dust-coloured'.