(n) A dimension used to describe the general size of an object, usually expressed in common fractions For example, a bolt might have a nominal size of 1/2"
The rough-sawn size of a piece of lumber When purchasing planed lumber it is sold by its nominal, rough-sawn, size For example a 2"x4" is the nominal size for a board whose actual dimension is 1 4" x 3 25"
The rough size of a member before planing The ordinary commercial size by which timber or lumber is known and sold on the market, but it may differ from the actual size
As applied to timber or lumber, it is the size by which lumber or timber is known and sold This size is often different from the actual size of the lumber