Princeton's WordNet

1. olive drab, drab(noun)

   a dull greyish to yellowish or light olive brown

2. olive drab, olive-drab uniform(noun)

   military uniform of the United States Army; made from cloth of a dull olive color

3. olive drab(adj)

   a cloth of an olive-brown color used for military uniforms

4. olive-drab, drab(adj)

   of a light brownish green color