Wood Terms - A Lumber Glossary from A - Z

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

Wood Terms that Start with "U"

Lumber Glossary Term	Definition
Underbrush	The brush under a stand of timber.
Undercut	A wedge-shaped notch cut in the base of a tree to govern the direction of its fall. This is also known as a box or a notch.
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.
Uneven-Aged Management	A Silvicultural system in which individual trees originate at different times and result in a forest with trees of all ages and sizes. Harvest cuts are on an individual-tree selection basis.
Unloaded Deflection	The vertical distance between the chord and the unloaded skyline, measured at mid-span.
Unmerchantable Wood	Material that is unsuitable for conversion to industrial wood products due to size, form, or quality. May include rough, rotten, and dead trees; the tops, limbs, and cull sections fro, harvested trees; or small and noncommercial trees.
Upper Stem Portion	Saw timber tree bole extending from above the merchantable top to as minimum four-inch top diameter outside bark or to the point where the central stems break into limbs.
Utility Knife	A cutting tool used in various trades and crafts for a variety of purposes. Designed to be lightweight, easy to carry and use.