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
(c) A long, thin strip used to strengthen a part, to cover a
Batten door (Arch.), a door made of boards of the whole
length of the door, secured by battens nailed crosswise.