Absorbency-  The extent to which a paper will take up and hold a liquid.
Acid Free  Indicates the paper is made without rosin and alum sizing which make the paper acidic.
Additive A- Mineral, chemical or dye added to pulp and coatings to give it special qualities such as opacity.

 B

Binder-  The adhesive used to stick the layer of coating together and to the paper or board surface; the most frequently used binder is starch but synthetic binders are also used to give improved performance. Synthetic binders are generally described as latex.
Blotting paper-  Highly absorbent paper which is sometimes watermarked; the ball point pen has drastically reduced the demand for this type of paper.
Board-  The papermaker's name for cardboard; it is thicker and heavier than paper and may be made of several layers laminated together.

C

Calcium Carbonate- Is added to paper to make it alkaline.  The cellulose in acidic papers degrades and crumbles away over time.  An alkaline paper will help absorb the atmospheric acidity found in pollution protecting the sheet.
Calendered-  Paper which has been smoothed and polished between sets of rollers called a calender; this process is usually done at the dry end of a papermaking machine.
Carton-  A container usually made of board but sometimes partially or totally of plastic; it is delivered by the carton manufacturer to the user in either flat or collapsed form.
Cartridge Paper- Tough, slightly rough surfaced paper used for a variety of purposes such as envelopes; the name comes from the original use for the paper which formed the tube section of a shotgun shell.
Chemical pulp-  See pulp.
Coating-  A layer of minerals applied to one or both sides of paper or board to improve brightness, gloss and printability; the mineral most often used is china clay, hydrated aluminium silicate, but calcium carbonate and titanium dioxide are also used; the coating is held together and stuck to the paper by a binder.
Cotton-   Cotton papers offer the purest form of cellulose available for papermakers to make the finest archival papers.
Cross Direction-  The direction, at right angles to the machine direction across a sheet or web of paper; paper expands about three times as much in the cross section as in the machine direction.

D

Dandy Roll- The roll on the wet end of a fourdrinier papermaking machine which is covered with a woven wire and carries a design to form a watermark in wet pulp.
Deckle Edges- The natural rough edges found on handmade and mould made paper. 
Dry End-  The part of a papermaking machine where the paper passes through steam-heated drying cylinders.

E

Embossed Mark- A logo that is embossed into the sheet to prove authenticity

Filler-  A material such as china clay or calcium carbonate which is added to make paper smoother and increase opacity.
Fourdrinier machine-  A papermaking machine that forms the paper in a continuous sheet on a wire belt; it was named after the Fourdrinier brothers who financed the first operational machine at the Frogmore Mill, Hertfordshire, in 1803.

G

Grammage- The term used to denote the weight of paper or board; the measurement used is the weight of a single sheet of one square meter, expressed as grammes per square meter (g/m²).

K

Kraft Paper-   Paper made from a type of chemical wood pulp; it may be bleached or unbleached and produces a strong paper which is used for wrapping and packaging; the term comes from the German word for strong

L

Machine Direction- The direction the paper is traveling along the paper machine.  With Fourdrinier made papers over 50% of the fibres position themselves with their lengths parallel to this direction.
Mechanical Pulp-  Pulp made by purely mechanical means, i.e. grinding wood; lignin and other impurities are not removed; fibre obtained from wood by either of the above methods is called primary, or virgin fibre.  See pulp.
Mould Machine-  A mould machine (cylinder mould machine) makes paper on a revolving wire covered cylinder. This process gives a type of mechanized hand made paper because the fibres lay randomly across the sheet making it much stronger than traditional fourdrinier made papers. 
Multi-ply Board Machine- A machine in which a number of plies of paper can be combined together in the wet state to produce thick cardboard.

Opacity- The property of a paper which prevents light being seen through it, measured scientifically as the amount of light reflected by the paper; in practice, in a paper with good opacity the printing or writing on one side cannot normally be seen from the other side.

Pulp-   Chemical pulp - Pulp made from wood chips by treating (cooking) with chemicals to separate out the cellulose fibres and dissolve the lignin, etc. binding them together; it can be bleached or unbleached.

Ream-   A unit of measurement for sheets of paper; normally 500.
Reel-   A continuous length of paper wound on a core.
Reel up-  The final process in making paper; after passing through the drying cylinders and, if appropriate, the calender rollers, the newly made paper is wound on to a jumbo reel: this is the reel up stage

S

Secondary Pulp-   Pulp made from waste paper and not directly from wood.
Sizing-   This process can either be applied on the surface of the sheet or in the sheet: in the first case starch or gelatine is applied to the surface to increase its strength and to resist the penetration of oil-based inks or paints(this process is carried out at the size press, which is about two-thirds of the way down the dry end); in the second case chemicals are added to the stock at the pulping stage before the sheet is formed: this is called internal or engine sizing and its purpose is to stop penetration of water-based inks or paints into the sheet.
Stock-   The wet pulp before it is fed on to a papermaking machine, or during the papermaking processes before it becomes a sheet of paper; contains around 99% water and 1% fibre.

W

Watermark-  A deliberate design or pattern made in the paper.  On a Mould Machine the design is sewn onto the wire covered cylinder so the paper is formed around the mark giving a good clear watermark.  On a Fourdrinier machine the watermark is created by a dandy roll as the stock passes through the wet end processes.  A watermark can be seen by holding the paper up to the light.
Wet end-  The first stages of a papermaking machine before the drying process; at the wet end, stock is fed in and much of the high percentage of water is eliminated by drainage, suction and press rollers, leaving a web of paper which then passes to the drying cylinders
Wood Free-  Paper made wholly from chemical pulp and free from wood-based impurities, such as lignin, which are present in mechanical pulp.
Wove Paper-  Paper first made as early as 1754 by forming it on a mould with a cover made from woven wire cloth, hence 'wove paper'; the paper has no watermark and an even opacity; it is a type of paper in common use today.