Meniscus

A meniscus (plural usu. menisci) is a curve in the surface of a liquid, produced in response to the surface of the container or another object. It can be either concave or convex.

A convex meniscus occurs when the molecules of the liquid repel the molecules of the container or object. This may be seen between mercury and glass in barometers.
Conversely, a concave meniscus occurs when the molecules of the liquid attract those of the container. This may be seen between water and glass.

Surface tension acts on concave menisci to pull the liquid up, and on convex menisci to pull the liquid down. This phenomenon is important in transpirational pull.

See also: Arthroscopic surgery, Capillary action, Transpirational pull, Where's my meniscus.