Source : Webster's Revised Unabridged Dictionary (1913)

Meta- \Met"a-\, Met- \Met-\ [Gr. ? between, with, after; akin to
   AS. mid with, G. mit, Goth. mi[thorn], E. mid, in midwife.]
   1. A prefix meaning between, with, after, behind, over,
      about, reversely; as, metachronism, the error of placing
      after the correct time; metaphor, lit., a carrying over;
      metathesis, a placing reversely.

   2. (Chem.) A prefix denoting:
      (a) Other; duplicate, corresponding to; resembling; hence,
          metameric; as, meta-arabinic, metaldehyde.
      (b) (Organic Chem.) 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-}.
      (c) (Inorganic Chem.) Having less than the highest number
          of hydroxyl groups; -- said of acids; as,
          metaphosphoric acid. Also used adjectively.