WordNet sense 1 (a browning of the skin resulting from exposure to the rays of the sun):

burn, sunburn, suntan

WordNet sense 2 (ratio of the opposite to the adjacent side of a right-angled triangle):

tangent

WordNet sense 3 (a light brown the color of topaz):

topaz

WordNet sense 4 (being or having or characterized by hue):

chromatic

WordNet sense 5 (get a tan, from wind or sun):

bronze