What is the meaning of the word "vitreous"?

Definitions:

  1. of ceramics, having the surface made shiny and nonporous by fusing a vitreous solution to it copy to clipboard adjective
    • I prefer vitreous ceramics. copy to clipboard
  2. relating to or resembling or derived from or containing glass copy to clipboard adjective
    • These vitreous rocks will be a nice addition to my collection. copy to clipboard

Synonyms: