WordNet records no synonym and no antonym for khaki. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a sturdy twilled cloth of a yellowish brown color used especially for military uniforms
1 of the 2 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for khaki.
Synonyms, antonyms and the broader and narrower relations for khaki come from Princeton University’s WordNet. Full sources and licences.