VERB (2)

1. change into glass or a glass-like substance by applying heat;

2. undergo vitrification; become glassy or glass-like;

The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vitrify \Vit"ri*fy\, v. t.
   To become glass; to be converted into glass.
   [1913 Webster]

         Chymists make vessels of animal substances, calcined,
         which will not vitrify in the fire.      --Arbuthnot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vitrify
    v 1: change into glass or a glass-like substance by applying
         heat
    2: undergo vitrification; become glassy or glass-like