upperside

Upperside is a noun describing the upper surface or top side of an object, opposite of underside. The term is used in several disciplines, including botany, zoology, and materials science, to distinguish the top-facing or exterior surface from the bottom or interior side.

In botany, the upperside of a leaf refers to the adaxial surface, which is typically the sun-facing side and can differ in color, cuticle thickness, and stomatal distribution from the lower (abaxial) surface. Stomatal patterns vary by species; some plants have most stomata on the lower surface to conserve water, while others may have stomata on both sides.

In zoology and entomology, the upperside corresponds to the dorsal or top side of an animal, such as the upper side of a butterfly’s wings or a reptile’s back. Wing uppersides often carry distinctive coloration and patterns used for camouflage, signaling, or thermoregulation, and may contrast with the underside.

In textiles and manufacturing, upperside can refer to the exterior or “right” side of fabric or leather, as opposed to the underside or lining. The term is also used in horticulture to indicate which surface is exposed to sunlight during growth or handling.

See also: underside, dorsum, adaxial, abaxial, right side, left side.