- Lumber that was dried, usually outside, to an equilibrium moisture content with the air it was exposed to. Any lumber below 30% moisture content is classified as air dried.
- Angel Step or Angel Stairs is a figure pattern found in lumber cut from trees that have twisted trunks, and is common in maples and walnuts. The figure on the board is characterized by short, delicate curls progressing up the board on a tangent, starting and ending out of nowhere - the image of a spiral staircase. The figure goes around the log; to achieve that image on the face of the board, the log should be flat sawn.
Annual growth rings
- The layer of wood growth put on a tree during a single growing season. The annual growth rings of many species (e.g., oaks and pines) are readily distinguished because of differences in the cells formed during the early and late parts of the season. In some temperate zone species (black gum and sweetgum) and many tropical species, annual growth rings are not easily recognized.
The Wood Glossary