Feather-edged

Having a feather-edge; also, having one edge thinner than the other, as a board; -- in the United States, said only of stuff one edge of which is made as thin as practicable.

1. Horizontal timber board thicker at the bottom than at the top, i.e. tapered in section, normally used for clap-boarding.

2. Type of coping with one edge thicker than the other, so it drains in one direction.