Source : Webster's Revised Unabridged Dictionary (1913)

Vitrify \Vit"ri*fy\, v. t. [imp. & p. p. {Vitrified}; p. pr. &
   vb. n. {Vitrifying}.] [F. vitrifier; L. vitrum glass +
   -ficare to make. See {Vitreous}, {-fy}.]
   To convert into, or cause to resemble, glass or a glassy
   substance, by heat and fusion.