In chemistry, it means a substance that can act as either acid or base. An example is amino acids and water. See also amphiprotic.
... area of 5.9 km² (2.3 mi²). 5.4 km² (2.1 mi²) of it is land and 0.6 km² (0.2 mi²) of it is water. The total area is 9.61% water. ...