Wood Terms - A Lumber Glossary from A - Z

A complete "Woodipedia" of lumber terms for experts & amateur woodworkers alike.

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Woodipedia Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Wood Terms that Start with "R"
Lumber Glossary Term Definition
R/L (RL)

Random Lengths

R/S Resawn
R/W (RW)

Random Widths


R/L (RL)

Rack and Pinion A system using two gears, one round, and one flat, to move a part. An example would be a drill press; a round gear connected to a handle works with a flat gear on the column to raise and lower the table.

Coincident with a radius from the axis of the tree or log to the circumference; in a round timber or piece of lumber, a line or surface extending outward from the heart-center; a radial surface is always edge-grain.

Radial Arm Saw A circular saw that runs on an overhead track; the track mechanism swings in relation to the table to make miter cuts.
Radial Drill Press

A drill press with the head mounted on a tube which is laterally and vertically adjustable. This type gives greater throat clearance but is not as solid as a conventional drill press so run out can be a problem.

Radial Shrinkage Shrinkage in a piece of lumber that occurs across the growth rings as it begins to dry.

The sloping main line of the roof frame.

Rail A horizontal board that runs along the underside of a table; the horizontal part of a raised panel door.
Rail Post

A vertical structural support for the railing, sometimes also supporting the deck itself and extending down to a footing. Rail posts are thicker than balusters and are attached with bolts to the joists or beams.

Railroad Tie A piece of industrial lumber used to support rails on a roadbed. In Britain and other countries it’s known as a “sleeper”.
Raised Grain

The roughened condition of sanded wood when the hard latewood rises above the soft earlywood when moisture is applied.

Raised Panel

A piece of wood that is the center of a frame and panel assembly.


The angle at which the leading edge of the teeth are cut on a saw blade.


A tooth set that has a uniform set angle and a three tooth set sequence of left, right, and straight.

Ram Set Gum

A nail gun used in construction and manufacturing to join materials to hard substances such as steel and concrete.

Random Lengths

Lumber of various lengths, usually in even two-foot increments. Lumber offered as random-lengths will contain a variety of lengths which can vary greatly between manufacturers and species. A random-length loading is presumed to contain a fir representation of the lengths being produced by a specific manufacturer.


A long and flat steel tool with raised teeth for shaping wood; some rounded on one side.

Rate of Growth

The speed at which a tree increases in size. This may be measured radically in the trunk, or in the dimension of the crown or other tree part. One unit of measure in wood is in number of annual growth rings per inch.


A generic term used to describe certain tool movements, such as the cone-to-slip engagement on permanent packers or plugs.


A ribbon like figure caused by the strands of cells which extend across the grain in quarter-sawn lumber.

RC Red Cedar



A wooden or metal structural member connecting a logging trailer to a truck tractor.

Reaction Wood

Abnormal wood tissue that was formerly in a leaning tree. Reaction wood is very unstable and extremely prone to warping and cupping when sawn into lumber. This wood has distinctive anatomical and physical characteristics. This characteristic is typical in parts of leaning or crooked stems and in branches; it tends to restore to the original position of the branch or stem if this has been disturbed. This is also known as tension wood.

Reciprocating Saw

A portable power saw with a reciprocating blade. Can be used with a variety of blades depending on the application and kind of cut; generally has a plate that rides on the surface that is being cut.


An exceptionally large Californian conifer, Sequoias semervirens, which yields red wood. This is a hot favorite as a decking timber because of the natural decay resistant qualities and beautiful tones.

Red Oak
  • Pinkish with a red tinge
  • Mostly straight grained
  • Coarse textured
  • Medium bending strength
  • High crushing strength
  • Used for flooring, furniture, and interior joinery.

Restocking an area with forest trees.

REG Regular

Renewal of a tree crop, either by natural or artificial means.


A statistical technique used to evaluate relationships among variables.



Relative Humidity The amount of moisture in the air that is measured as a percentage of the total amount of moisture the air can hold at a particular temperature. This is known as relative humidity. The ideal relative humidity for a home is between 35% and 45%. Too much above or below these levels can lead to problems occurring.
Reload To transfer logs from one mode of transportation to another or between vehicles.

To salvage small timber, culls, and other residuals following the main logging operation.

Remote Deck

A freestanding platform located away from the house, typically placed for a good view.


Trees remaining after an intermediate or partial cutting of tree crops or stands. In general, residuals are by products of an operation. Examples are chips from lumber production and hog fuel from any wood processing operation. This is also known as waste.

Residual Stand

Trees remaining in an area after the cutting operation has been completed.

Residual Value

The actual or assumed value of a machine after it has been fully depreciated.


Wood or bark that is left after a manufacturing process.


The property where a strained body gives up its stored energy on the removal of the deforming force.


An organic material that has an indefinite and often high molecular weight, exhibits a tendency to flow when subjected to stress.

Resin Ducts

Intercellular passages that contain and transmit resinous materials.

Retention by Assay The determination of a preservative retention in a specific zone of treated wood by extraction or analysis of specified samples.

The study of the deformation and flow of matter.


A pile of evenly stacked cordwood, stave, bolts, or other short-length wood.

Ridge Beam

A horizontal timber to which the tops of rafters are fastened. This is also called a ridge board or a roof tree.

Ridge Pole

A horizontal timber which connects rafter pairs at the peak.

Ridge Purlin

The beams connecting rafter to rafter at the apex.

Rift Lumber

Diagonally grained lumber.


To install the blocks and lines used in a cable logging system.


Cables, blocks, and other equipment used in yarding logs.


A strip of land on which a road is to be constructed.


A circular rot in a log. Any rot localized mainly in the springwood of the growth rings, giving a concentric pattern of decayed wood in the cross section of a tree or log.

Rink-Shank Nail

A nail with grooves and ridges around the shank to prevent the nail from popping out of the wood as the wood contracts and expands because of changes in moisture and temperature.

Riparian Right

A right of someone owning land located on the bank of a natural watercourse, such as a river, lake, or tidewater, to access or use the shore, bed, or water.

Rip-Cut (Ripping)

A cut made parallel to the grain of a board.

Ripple Marks

Fine horizontal striations visible on the tangential longitudinal surfaces of certain wood. Due to the stories arrangement of the rays or of the axial elements or of both.


Rough stones of various sizes placed compactly or irregularly on the ground surface to prevent scouring by water or debris.


Redwood Inspection Service


The vertical distance from one stair tread to another.


The vertical piece between two stair steps.

Robertson Head

A screw head requiring a driver with a square tip. This is also referred to as a socket head.


A roller that has an absorbent surface used for spreading paint.

Roof Truss

An engineered building component that supports the roof in place of rafters. Roof trusses are constructed in a triangular shape with a number of interconnected pieces that spread a load evenly across the truss.


Roll-over protective structures that protect the operator if a machine overturns.


A machine that peels bark using knives.

Rotary Planar

A power hand tool with rotating blades that smoothes the surface of material.

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.


Period of years between establishment of a stand of timber and the time when it is considered ready for final harvest and regeneration. The planned number of years between the regeneration of a timber stand and its final cutting.

Rough Cut

Lumber that has not been dressed (surfaced) but which has been sawn, edged, and trimmed to at least show saw marks in the wood on the four longitudinal surfaces on each piece for its overall length.

Rough Lumber

Lumber which has not been dressed or surfaced but has been sawn, edged, and trimmed.

Rough-Edge Lumber

Boards having attached bark on both edges.


Lumber that is either green or dried that has not been dressed (planed).

Round Wood

A length of cut tree generally having a round cross-section, such as a log or bolt.

Round Wood Products

Logs, bolts, or other round sections cut from trees for industrial or consumer use.


A high speed motor with handles and an adjustable base with a collet that accepts profile bits to cut dados, rabbets, and shapes.

Rub Bearing

A ball bearing rub collar near the top or bottom of a spindle shaper that is used to keep the work piece a fixed distance away from the cutters.

Rub Tree

A tree used as a fender or pivot to protect the remaining stand during yarding.

Rule Joint

A joinery method used in drop left tables where the tabletop has a convex profile and the left has a concave cut. The two pieces are joined by a hinge.


The horizontal distance from one stair riser to another, the depth of a stair step.


The amount of wobble in a shaper or router.

Running Line

A moving cable

Running Skyline

A system of two or more suspended moving lines, generally referred to as main lines and haul-back lines. Will provide lift and travel to the load carrier when tension is properly applied.


Random widths and random lengths.



Woodipedia Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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