Source : Webster's Revised Unabridged Dictionary (1913)

Para- \Par"a-\ [Gr. ? beside; prob. akin to E. for- in forgive.
   Cf. {For-}.]
   1. A prefix signifying alongside of, beside, beyond, against,
      amiss; as parable, literally, a placing beside; paradox,
      that which is contrary to opinion; parachronism.

   2. (Chem.) A prefix denoting:
      (a) Likeness, similarity, or connection, or that the
          substance resembles, but is distinct from, that to the
          name of which it is prefixed; as paraldehyde,
          paraconine, etc.; also, an isomeric modification.
      (b) Specifically: (Organ. Chem.) That two groups or
          radicals substituted in the benzene nucleus are
          opposite, or in the respective positions 1 and 4; 2
          and 5; or 3 and 6, as paraxylene; paroxybenzoic acid.
          Cf. {Ortho-}, and {Meta-}. Also used adjectively.