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 1 1 in.
in width. The word comes through the Fr. planche (from postAugustan, Lat. planca, a nasalized adaptation probably of Gr. irXd, 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.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)