A plate in timber framing is "A piece of Timber upon which some considerable weight is framed...Hence Ground-Plate...Window-plate [obsolete]..." etc.
[1] Also called a wall plate,[2] raising plate,[3] or top plate,[4] An exception to the use of the term plate for a large, load-bearing timber in a wall is the bressummer, a timber supporting a wall over a wall opening (see also: lintel).
Other load-bearing timbers use the term plate but are not in the wall such as crown plate, a purlin-like beam carried by crown posts in roof framing, and a purlin plate which supports common rafters.
In platform framing there are three types of wall plates and are located at the top and bottom of a wall section, and the two hold the wall studs parallel and spaced at the correct interval.
Each type continues in a piecewise fashion around the whole perimeter of the structure.