1911 Encyclopædia Britannica/Plank

PLANK, a flat piece of timber, sawn and planed; it is technically distinguished from a “board” by its greater thickness, and should measure from 2 to 4 in. in thickness and from 10 to 11 in. in width. The word comes through the Fr. planche (from post-Augustan, Lat. planca, a nasalized adaptation probably of Gr. πλάξ, something flat, especially a flat stone. The use of the word “plank” in the sense of an article in a political programme is of American origin and is due to the use of “platform” for the programme itself.