1. Form or shape beforehand or determine the shape of beforehand
   "The dental technician preformed the crown"
    
2. Form into a shape resembling the final, desired one
   "They preformed the plastic parts before the final moulding process"

Derived forms: preforms, preforming, preformed

Type of: forge, form, mold [N. Amer], mould [Brit, Cdn], shape, work

Encyclopedia: Preform