sub·duc·tion 
(səb-dŭkshən)
(səb-dŭkshən)n.
A geologic process in which one edge of one crustal plate is forced below the edge of another.
[French, from Latin subductus, past participle of subdūcere, to draw away from below : sub-, sub- + dūcere, to lead; see deuk- in the Appendix of Indo-European roots.]
sub·duct v.
sub·ductal (-təl) adj.