The Collaborative International Dictionary of English v.0.48:

Antipodal \An*tip"o*dal\, a.
   1. Pertaining to the antipodes; situated on the opposite side
      of the globe.
      [1913 Webster]

   2. Diametrically opposite. "His antipodal shadow." --Lowell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

antipodal
    adj 1: relating to the antipodes or situated at opposite sides
           of the earth; "antipodean latitudes"; "antipodal regions
           of the earth"; "antipodal points on a sphere" [syn:
           antipodal, antipodean]
    n 1: the relation of opposition along a diameter [syn:
         antipodal, antipodal opposition, diametrical
         opposition]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "antipodal":
   antipodean, antithetic, antithetical, confronting, contradictory,
   contrapositive, contrary, converse, counter, diametric,
   diametrically opposite, eyeball-to-eyeball, facing, inverse,
   obverse, opposing, opposite, polar, polaric, polarized, reverse