subduction

from WordNet (r) 3.0 (2006)

subduction
    n 1: a geological process in which one edge of a crustal plate
         is forced sideways and downward into the mantle below
         another plate

from The Collaborative International Dictionary of English v.0.48

Subduction \Sub*duc"tion\, n. [L. subductio.]
   1. The act of subducting or taking away. --Bp. Hall.
      [1913 Webster]

   2. Arithmetical subtraction. --Sir M. Hale.
      [1913 Webster]