the.com/olive drab

means A dull yellowish-brown-green shade used almost universally for military uniforms and equipment because it blends into most natural terrain.

from The term pairs 'olive,' from the grayish-green color of olive fruit and foliage (ultimately from Latin 'oliva'), with 'drab,' which originally meant a thick undyed woolen cloth (from French 'drap,' cloth) before coming to mean a dull brownish color. Armies adopted olive-toned dyes in the early 20th century as a practical shift away from bright, visible uniforms — the same era that gave the shade its lasting name.