Use this resource for picture framing terms.
While not all picture framing terms are included in this list, it highlights the terms most often used.
For more picture framing terms see the links at the bottom. Acid-free paper: lignin, sulfur-free with a basic or neutral Ph. Use in conservation of framed photos, memorabilia, etc. Acrylic: Methyl methacrylate. Resistant to weathering, thermoplastic polymer. Another temr for Plexiglas in the framing world. ATG Tape: Transfer tape used in mounting photos and artworkand to adhere back paper to frame Back paper: Covers the back of the frame Collage: Work of art composed of elements not commonly associated with one another; ie newspaper clippings, pins, photos, tickets. Double Mat: The use of two mats in a frame, often for aesthetic appeal. Foam Core: Easily cut material used for the backing of prints, designs and paintings. Consists of three layers. Matting: A piece of fabric or other material used as a protective barrier/surface material. Moulding: The material used to make the actual frame. Can be made from wood, polymer or metal. Mounting: affixing items onto the mat board to secure for framing purposes. Shadow Box: Any raised, framed object. 
Sources: www.Dictionary.com http://www.americanframe.com/blogs/ask-mike/february-2014/diy-picture-framing-tips-the-proper-way-to-back-a.aspx https://en.wikipedia.org
