1. In medicine and biology, a prefix denoting the concept of after, subsequent to, behind, or hindmost.
2. In chemistry, an italicised prefix denoting joint, action sharing.
3 (m-). In chemistry, an italicised prefix denoting compound formed by two substitutions in the benzene ring separated by one carbon atom, i.e., linked to the first and third, second and fourth, etc., carbon atoms of the ring. For terms beginning with meta-, or m-, see the specific name.
Origin: G. After, between, over