meniscus science definition

1. A lens that is concave on one side and convex on the other.
2. The curved upper surface of a column of liquid in a container. The surface is concave if the molecules of the liquid are attracted to the container walls and convex if they are not. See also surface tension.
3. A piece of cartilage shaped like a crescent and located at the junction of two bones in a joint. The meniscus acts to absorb shock.

meniscus

left: Water and glass molecules are attracted to each other, causing the surface of the water to attach to the glass and curve upward.

right: Mercury and glass molecules are repulsed by each other, causing the surface of the mercury to curve downward and away from the glass.