In chemistry, a meniscus is the upward or downward curve seen at the top of a liquid in a container). The curve is caused by surface tension and adhesion between the liquid and the container. The nature of the curve, whether upward (convex) or downward (concave), depends on the surface tension of the liquid and its adhesion capacity to the wall of the container. Most liquids, including water, show a concave meniscus, but a convex meniscus appears when molecules of a liquid are strongly attracted to each other rather than to the wall of the container).

The meniscus is important in laboratory measurements because it can affect the accuracy of volume measurements. To accurately and precisely measure the volume of a liquid in a laboratory graduated measuring glassware or plasticware, it is important to read the meniscus correctly. Manufacturers of glassware and other tools calibrate their measurement marks to account for the meniscus, which means that any instrument is calibrated for a specific liquid, usually water).

The formation of menisci is commonly used in surface science to measure contact angles and surface tension). In a contact angle measurement, the shape of the menisci is measured with a balance or optically with a digital camera). In a surface tension measurement, the measurement probe has a contact angle of zero, and the surface tension can be obtained by measuring the mass of the menisci).

In summary, a meniscus in chemistry is the curve seen at the top of a liquid in a container, caused by surface tension and adhesion between the liquid and the container. It is important in laboratory measurements and is commonly used in surface science to measure contact angles and surface tension.