The Greek verb apoteleo means to complete, to bring to full completion, to finish or perfect. It combines apo- (intensive) and teleo (to complete/accomplish). It appears twice in the New Testament, once in James's description of the process from desire to death, and once in Luke of Jesus' work.
Apoteleo is used memorably in James 1:15: 'Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown [apotelestheisa], gives birth to death.' The word describes sin completing its deadly work — brought to full maturity and bearing its lethal fruit. This is a sobering biological metaphor: sin has a life cycle, and if not interrupted, it reaches full term and brings spiritual death. The verb also appears in Luke 13:32 where Jesus says He will 'complete' His work on the third day, pointing to the accomplished redemption of the cross. Apoteleo marks finality — for better or worse.