Other forms: battened; battens; battening
A batten is a strip of wood or metal that's used to provide structure to a roof or wall or as a support for a sail or hatch on a ship.
On a boat, one flexible type of batten supports the shape of the mainsail, and another batten is a sturdy bar that keeps the hatch securely closed during a storm. As a verb, to batten is "to fasten securely," particularly using a batten. Batten down the hatches also has a figurative meaning — to get ready for difficult or tumultuous times ahead. Batten comes from baton and its Latin root, which means "stout staff or stick."