The Collaborative International Dictionary of English v.0.48:

Batten \Bat"ten\, n. [F. b[^a]ton stick, staff. See Baton.]
   A strip of sawed stuff, or a scantling; as,
   (a) pl. (Com. & Arch.) Sawed timbers about 7 by 2 1/2 inches
       and not less than 6 feet long. --Brande & C.
   (b) (Naut.) A strip of wood used in fastening the edges of a
       tarpaulin to the deck, also around masts to prevent
       chafing.
   (c) A long, thin strip used to strengthen a part, to cover a
       crack, etc.
       [1913 Webster]

   Batten door (Arch.), a door made of boards of the whole
      length of the door, secured by battens nailed crosswise.
      [1913 Webster]