To discolor or scorch by the sun; tan: said especially of the skin or complexion.To be discolored or tanned by the sun.n. A burning or scorching by the sun; especially, the tan occasioned by the exposure of the skin to the action of the sun's rays.n. In botany, same as heliosis.n. The injury to the leaves or bark of plants produced by the hot sun causing excessive or too rapid evaporation of the water content of the cells, and thus killing the tissues, which become brown. The tips and margins of rapidly growing leaves and the cambium layer of the bark of young trees are most frequently affected. Also called sun-scald. Compare heliosis.