Quarter-sawn: A method of cutting lumber where the annual rings are relatively perpendicular to the face of the board. Quarter-sawn lumber tends to be more dimensionally stable than other forms of lumber, such as plain sawn.
Rabbet: A cut partway through the edge of a board that is used as a part of a joint.
Radial Shrinkage: Shrinkage in a piece of lumber that occurs across the growth rings as it begins to dry.
Rail: (1) A horizontal board that runs along the underside of a table. (2) The horizontal part of a raised panel door.
Raised Panel: A piece of wood that is the center of a frame and panel assembly.
Ray: A ribbon like figure caused by the strands of cells which extend across the grain in quarter sawn lumber.
Reaction Wood:Abnormal wood tissue that was formed in a leaning tree. Reaction wood is very unstable and prone to warping and cupping when sawn into lumber.
Ripcut (Ripping): A cut made parallel to the grain of a board.
Rotary-cut Veneer: Veneer which was cut from a log in one long sheet. Rotary cut veneer is cut from a log like a roll of paper towels.
Rub Bearing: A ball bearing rub collar near the top or bottom of a spindle shaper that is used to keep the workpiece a fixed distance away from the cutters.
Rule Joint: A joinery method used in drop leaf tables where the tabletop has a convex profile and the leaf has a concave cut. The two pieces are joined by a hinge.
Runout: The amount of wobble in a shaper or router.
Sap: The water in a tree which is rich in minerals and nutrients.
Sapwood: The new wood in a tree that lies between the bark and the Heartwood. Sapwood is usually lighter in color and becomes heartwood as the tree ages.
Scarf Joint: A woodworking joint that is made by cutting or notching two boards at an angle and then strapping, gluing, or bolting them together.
Seasoning: The process of removing the moisture from green wood to improve its workability and stability.
Selects: In softwood, lumber which has been graded strictly for its appearance. In hardwood, lumber which is one grade below first and second.
Sliding Dovetail Joints: A sliding dovetail joint is similar to a tongue and groove joint except the tongue and grove are matching dovetails.
Softwoods: Generally lumber from a conifer such as pine or cedar. The name softwood does not refer to the density of the wood. There are some hardwoods, such as Balsa, which are softer than some softwoods, like Southern Yellow Pine.
Sound: A term referring to a board which has no or very few defects which will effect its strength.
Specific Gravity: The ratio of the weight of wood to an equal volume of water. The higher the specific gravity, the heavier the wood.
Spermatophyte: Plants that reproduce by seeds. This includes almost all plant species.
Spindle: The threaded arbor on a shaper that holds the cutters.
Spline: A thin piece of wood that fits in the mating grooves cut into two pieces of wood.
Squeeze-out: A bead or drops of glue that are forced out of a joint when pressure is applied.
Stain: 1) A discoloration in wood caused by a fungus or chemicals. 2) A die or pigment used to color wood.
Sticker: A thin wood strip that is inserted between stacks of green wood to allow air to flow through the stack to ensure proper drying.
Stile: The vertical part of a raised panel door.
Surfaced Lumber: A piece of wood that has been planed smooth on one or more surfaces.
Surfacing: The way a piece of lumber has been prepared at the lumber mill.
Tack Time: The amount of time it takes for an adhesive to set-up before it can form a bond.
Taper: A piece of wood that has been cut so that it is wider on one edge than the other.
Tearout: The tendency for a blade to splinter the last part of a piece of wood during crosscutting.
Tempered Hardboard: Dense fiberboard that has been specially treated to increase its durability, strength, density, and moisture resistance.
Template: A pattern. Often a template is made of hardboard and used with a pilot bit to route a shape in a board.
Template guide: A jig mounted to the bottom of a router that is used to keep the router on the profile of a template when routing with a non-pilot beating bit.
Tenon: A protrusion from a board that fits into a matching mortise to form a joint.
Through Dovetail Joint: A method of joining wood where the interlocking pins and tails of the dovetail joint go through the side of its mating piece.
Tongue and Groove: A joinery method where one board is cut with a protruding "groove" and a matching piece is cut with a matching groove along its edge.
Torque: The amount of force that is needed to turn an object such as a screw or bolt.
Twist: Warping in lumber where the ends twist in opposite directions. (Like twisting a towel Underlayment: A layer of plywood or other manufactured board used as a base material under finished flooring. Underlayment is often used as a substrate to increase the strength and/or smoothness of the flooring.
Veneer: A thin sheet of wood cut from a log.
Veneer-core Plywood: Plywood made from three or more pieces of veneer glued up in alternating grain patterns.
Warp: A defect in lumber characterized by a bending in one or more directions.
Wormholes: Holes and channels cut in wood by insects.