Definitions for "NOMINAL DIMENSION"
A dimension greater than a specified masonry dimension by the thickness of a mortar joint, but not more than 1/2 in.
Within established range of manufacturing tolerances.
A dimension which is greater than the actual dimension of lumber or masonry. In lumber, supposedly the wood size before it has been milled. A brick nominal size usually allows for a 1/2-inch mortar joint to give the full nominal dimension.