This is great reference resource and I must cop to lifting it directly off of the Parker Jordan website.  I imagine that they did the same.  Although it is not complete, it's hard to improve on existing excellence.

I will have a similar Art Terminology reference coming in the near future.

ATG: Initials that stand for "adhesive transfer gum," a double-sided tape primarily used to 
apply dust covers or to hold mats together in multiple mat designs. The tape comes on a paper carrier and is generally, but not necessarily, applied with a special applicator--an ATG gun. 

Acid Burn: A brown line or brown coloration on paper that is the result of prolonged 
contact with acidic cardboard or other materials. Acid burns often are seen on the face of 
paper artwork that was matted with acidic cardboard mats.

Acid Free: A term used to describe adhesives, papers, matboards and other framing supplies that 
have no acid in them. Acid-free materials should be used when framing works of art on paper. 
Matboards, mounting boards, tapes, envelopes and other framing materials all are 
available in acid-free varieties. Some have been chemically treated to remove impurities; others, such as those made of 100 percent pure cotton rag, never contained acid and are generally the best choice for framing fine art.

Acrylic: Clear plastic sheeting used in framing applications. Acrylic can be used instead of glass 
to glaze a picture; acrylic also is used to make boxes to hold large pieces and three-dimensional objects.

Backing board: General term for the material used to fill the back of the frame; most often scrap 
matboard or foam-core board. The backing board is held in place by glazier's points or brads and is covered with a dust cover (kraft paper, usually). The English refer to mounting board as "backing board." So, too, do some U.S. conservators.

Bevel: Generally refers to the 45-degree angle on the window opening of a matboard that has been cut with a mat cutter. When such a cut is made, the core of the matboard is exposed. A standard bevel, which leaves the core of the matboard showing around the window opening in front, is cut from the back of the matboard. Unless otherwise specified, it is this cut that framers generally mean when they refer to the bevel. If a mat is cut with a reverse bevel, the 45-degree angle cut slants away from the surface of the matboard so the matboard core is not seen from the front. A reverse bevel often is used when a visible bevel would be a distractingelement in the design. A reverse bevel is usually cut from the front; however, if the mat cutter head is reversed, this bevel also can be cut from the back.

Blocking: Refers to straightening and shaping a piece of fabric or needleart. The material is dampened, stretched slightly to straighten, and tacked to a board. It must be allowed to dry while tacked before it is mounted.

Bloom: A white or milky haze on an oil painting. It is caused by water vapor in the painting varnish.

Brad: A small nail used in joining frames and, sometimes, in securing the backing board into the frame.

Chops: Picture frame mouldings that are purchased already cut to size (chopped) by the moulding supplier for a specific frame. Chops often are more expensive per foot to buy than the same pattern purchased in length.

Chop Service: The service offered by suppliers who make precut moulding available. Some suppliers also offer "chop and join" services in which the moulding is not only precut, but also is joined by the supplier before shipment to the framer. Many retailers use chops primarily for ornate, wide moulding that would be too expensive to inventory only for occasional orders, or to try out new patterns before stocking them.

Chopper: One of several tools used for mitering moulding. Choppers may be foot- or power-operated; there are some tabletop models operated by hand. Two blades come down from the top to cut both miters at once.

Compo: (Short for Composition) A plasterlike substance used in making decorative ornaments for frame finishing. Compo ornaments are applied to a wood frame base to give moulding an ornate, hand-carved look. Compo also can be used to repair or replace ornaments on a frame.

Conservation Framing: Using materials and techniques in the framing process to ensure artwork is not damaged by framing. Hinging the artwork instead of mounting it, using high-quality acid-free boards and mats, using nonstaining paste, and glazing with conservation glass or acrylic are generally accepted procedures used to help preserve artwork. The same procedures are sometimes referred to as "preservation framing." 

Conservation Mounting: 
The process of attaching the artwork to the backing board in a way that will not harm the art. Materials used include ragboard, rice or wheat paste, and mulberry hinges, or other inert (nondeteriorating or nonstaining) materials and processes. Many framers call this process "museum mounting" or "preservation mounting."

Distressing: 
A technique sometimes used on furniture and picture frame moulding to literally beat up the object with chains or other implements and leave random gouges in the wood before finishing. The treatment makes wood look old and worn.

Dry Mount, Dry Mounting: The process of using dry adhesive tissues to mount paper artwork or photographs to a board, using high heat and a dry mount press.

Dry Mount Press: One of a wide variety of machines that feature the use of heat, pressure and special adhesive tissues to mount artwork to board.

Dust cover: A protective paper sheet (usually kraft paper) attached to the back of the frame to protect 
the contents from dirt. The dust cover often is attached with ATG tape laid along the frame edges; a variety of glues also may be used to attach the dust cover.

Foam-core board: A lightweight, plastic-centered board sold in large sheets. Foam-core board is used as a  mounting board, as a backing board, and as a spacer in deep frames or shadow boxes.  Foam-core board also is used in routine mounting of needlework and paper art.  Foam-core board variations come from many manufacturers, with different compositions, colors and face papers.

Fillet: (1) A very thin moulding used as an accent in framing inside another moulding or liner. It is sometimes used under the glazing at the edge of the mat window opening. Some framers also refer to edge of an undermat (a thin border that shows around the artwork) as a fillet. (2) Any thick piece of paper or board or thin piece of wood glued to the moulding rabbet to hold the glass away from an unmatted piece of artwork. Another term for "fillet" in this second usage is "spacer."

Fitting: 
The process of putting together the pieces of the framing package: the joined moulding, glass, mounted artwork, matting, backing board, dust cover and hardware. Fitting includes cleaning the glass and checking the entire job for flaws before closing the frame.

Foxing: Mold growth on paper artwork (typically appearing as brown spots). Foxing is found  particularly on old prints and graphics, maps, letters and other documents.

French Mat: A mat with inked lines spaced at various intervals around a window opening. Often a  watercolor wash is used between the lines to create a decorative panel. Colored powder pastels or chalk may be used in place of the watercolor wash.

Gesso: A brush-on white primer used as base coat over raw moulding prior to painting or leafing.

Gilding: The process of applying gold leaf and/or burnishing powders to a prepared wood frame. See "gold leaf."

Glazing: A broad term that includes a wide variety of glass and acrylic products used to finish and protect framed artwork. Varieties include regular picture framing glass, conservation/preservation glass and acrylic, anti-reflective and nonglare glass. Many manufacturers carry products that offer combinations of these features.

Gold leaf: Very thin leaves of real gold that are burnished onto a wood frame that has been coated 
with several layers of other material in preparation. The process is painstaking and expensive because of the use of precious metal.

Heat press: A mounting press that uses a combination of heat and pressure to attach artwork to a 
backing board. (See dry mounting, dry mount press.)

Hinges: Materials used to mount artwork in conservation framing. Strips of Japanese or mulberry paper are torn; starch glue is applied to the strips. The paper art is attached to the acid-free mount only by these hinges. In recent years, a number of hinging products have been introduced, including strips of paste impregnated mulberry paper that are water-activated.

Joining: The process of putting together mitered sticks of moulding to make the frame. Joining requires applying glue to each corner, carefully placing the segments in the vise or joining machine, and then attaching the corners. If placed in a vise, the corners can be nailed by hand. If placed in a power joiner such as an underpinner, the segments will be held together by staples or wedges inserted by the machine from underneath. The nails are important because they hold the corner together firmly until the glue dries. However, glue is most important to provide a strong joint that will not separate easily.

Lacing: The conservation-approved way to mount a variety of types of needleart prior to framing. The artwork is centered on a mounting board, and the excess fabric is wrapped to the back of the board. With a needle and thread, the framer draws cotton thread through a corner of the fabric on one side and across to the opposite side; he continues back and forth across the work as if lacing a shoe. With lacing completed across two sides, the work is turned and the pattern is repeated for the remaining two sides, until the work is held firmly in place around the support board. Lacing is time-consuming and painstaking work.

Laminate:
Moulding featuring high-gloss plastic, leather, wood or other material applied over a wood core.

Leafing: The process of applying real gold or silver leaf or imitation leaf to a moulding or mat.

Length: Moulding ordered from a supplier in sticks of eight to 12 feet and stocked in inventory. It 
is cut to size by the framer after a customer orders a frame of that particular style. Also called "stick moulding."

Lip: The thin, projecting edge of the moulding that is just above the rabbet; mats and glazing 
generally fit under the moulding lip.

Liner: A moulding, usually fabric-covered, used inside the outer moulding in a frame design. A liner is not completely finished, so it would not be used as the only moulding for a frame. Liners often are used in place of mats on framed oil paintings.

Mat-board: A paper or rag board used over artwork to separate it from the glass. Mat-board generally is made up of three layers: the face paper, the core and the backing. Mat-boards come in a wide variety of thicknesses (plys), colors, textures and compositions, and many acid-free mat-boards are for conservation framing. Mat-boards can be carved, cut or painted to add decorative elements to the frame design. Various colors and textures can be stacked, spliced and combined in numerous ways.Mat-board usually has a whitish material in the center so that a white line (bevel) shows when it is cut. However, some mat-boards also have black or colored cores, resulting in a colored bevel when they are cut. Cores may be the same color as the face paper or a contrasting color. Colored-core mat-board expands the design possibilities for framers.

Mat Cutter: Equipment used to cut mat-boards. There are a wide variety of manual mat cutters on the market, including hand-held, straightedge, and circle and oval cutters. The primary components are a blade in a cutting head and some kind of guide device. In addition, several companies offer computer-operated mat cutters that can perform complex or volume mat cutting.

Matting: The process of cutting and placing a piece of mat-board, with a window opening cut, over or around artwork. The mat serves two functions: It protects the artwork by separating it from the glazing and providing air circulation; and it enhances the artwork it surrounds. It may be a highly decorative part of the design, or it may simply provide a restful area around the artwork.

Mitering: The process of cutting two corresponding angles in sticks or lengths of moulding. When joined together, the angles form the corner of the frame. A square or rectangular frame uses 45-degree miter cuts; frames with triangles or other shapes in the design require other angles for the miter.

Miter Saw: A saw that cuts moulding at an angle so it can be joined with another piece of moulding cut at a corresponding angle.

Moulding: The material used to build a frame. Mouldings can be wood, metal, plastic or laminate, 
and they may be purchased from suppliers in lengths/sticks or as chops.

Mounting: The procedure of securing artwork or an object to a surface to hold it in the frame. There 
are many methods of mounting, including dry mounting, wet mounting, spray mounting, vacuum mounting, lacing, stretching, stapling and hinging. It is important to choose the proper method to preserve the value of the items being mounted.

Non-Glare Glass: A glazing, usually etched on one or both sides, that eliminates reflections and glare from 
room lights. 

Oval Cutter: A machine especially built to cut circles or ovals in matboard. Some also are designed to cut glass and cardboard.

Profile: The shape or design of the moulding, including all carved or grooved elements.

Rabbet: The groove under the lip of the moulding that allows space for the mat, glass, art and 
mounting board.

Rag-board: A board manufactured from cotton or other fibers. Virgin ragboard was the only choice 
of conservators for many years and is still considered a high-quality choice for conservation framing. However, many conservators today find that chemically neutralized colored boards made of purified wood fibers also are acceptable for use in conservation.

Restoration: Work done on a piece of artwork to make it resemble its original condition. It really isn't  "restoring," since nothing can bring the art back to its exact original state. Restoration may involve relining, in-painting, cleaning, revarnishing, etc., and is generally best left to experts in the field.

Shrink-Wrap: The process of wrapping something with plastic film, then sealing and tightening the film
with heat. Several companies offer shrink-wrapping equipment. Sometimes galleries shrink-wrap artwork that has been mounted to a display board; this protects the art when customers handle it.

Spandrel Frame: A frame made with a circular or oval opening within a square or rectangle.

Strainer: A wood support frame to which the canvas of oil paintings or the fabric of needleart is sometimes attached. Strainers also can be inserted behind large framed items to stabilize the frame. Strainers are constructed as solid frames and are not adjustable. (See "Stretcher.")

Stretcher: A support frame made of wood onto which the canvas of oil paintings or needleart can be mounted. A stretcher has adjustable corners that allow for periodic tightening (stretching) of the canvas, unlike a strainer (see above) which is solidly joined at the corners.

Tacking Iron:
Small iron used in dry mounting. It attaches the tissue and the paper to one spot on the mounting board so that nothing in the package shifts as it is placed in the press.

Under-Pinner: Power machine that joins frames rapidly and efficiently. It generally is operated by a foot 
pedal and can be either air-powered or manually operated. The two pieces of moulding are glued and placed in vises that hold them snugly together; a staple or V-shaped fastener shoots up from underneath and joins the pieces. 

V-Groove: The process of cutting two close, facing bevels into matboard so they form a "V" when the board is taped back together.

Vacuum Mounting: A cold mounting system using the pressure of a vacuum press to mount paper art and 
fabrics to a mounting board. Either sprays or wet adhesives such as paste can be used.

Vacuum Press: A press that creates a vacuum to generate enough pressure to mount artwork to a backing 
board. Some presses are combination heat/vacuum presses.