Not telling
A flat piece of wood is called a board.
PANEL
A piece of wood siding is called a clapboard or a plank.
A thin piece of wood is called a "slat."
A thick piece of wood is called a plank. It is a long, flat piece of wood that is often used in construction or woodworking projects.
Drift wood
The end result is called "petrified wood".
a piece of wood is called log
The decorative wood on a staircase is called "wainscot"
A piece of permineralized wood is called petrified wood. It forms when wood becomes fossilized by minerals replacing the organic material over time, resulting in a stone-like appearance while retaining the structure of the original wood.
A long piece of sawed lumber or wood is called board
The backboard.