(1):

(n.) The sides of a ship above the upper deck.

(2):

(n.) That which secures against an enemy, or defends from attack; any means of defense or protection.

(3):

(n.) A rampart; a fortification; a bastion or outwork.

(4):

(v. t.) To fortify with, or as with, a rampart or wall; to secure by fortification; to protect.