Cement  —n. 1 powdery substance of calcined lime and clay, mixed with water to form mortar or used in concrete. 2 similar substance. 3 uniting factor or principle. 4 substance used in filling teeth, doing hip replacements, etc. —v. 1 a unite with or as with cement. B establish or strengthen (a friendship etc.). 2 apply cement to. 3 line or cover with cement.  cementation n. [latin caedo cut]