That two replacing radicals, in the benzene nucleus, occupy the relative positions of 1 and 3, 2 and 4, 3 and 5, 4 and 6, 5 and 1, or 6 and 2; as, metacresol, etc. See Ortho-, and Para-.
MET-
Meaning of MET- in English
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012