underhew

from The Century Dictionary.

• To hew less than is proper or usual; hew (a piece of timber which should be square) in such a manner that it appears to contain a greater number of cubic feet than it really does.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To hew less than is usual or proper; specifically, to hew, as a piece of timber which should be square, in such a manner that it appears to contain a greater number of cubic feet than it really does contain.