The Collaborative International Dictionary of English v.0.48:

Anti-trade \An"ti-trade`\, n.
   A westerly wind which blows nearly continuously between
   30[deg] and 50[deg] of latitude in both the northern and the
   southern hemisphere.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

antitrade
    n 1: winds blowing from west to east and lying above the trade
         winds in the tropics [syn: antitrade wind, antitrade]