Cacao. Chocolate nuts.
Cackle. To cover a cable spirally with old three-inch rope to protect it from chafing.
Callous (of a broken bone). The new bony tissue formed between and around the fractured ends of a broken bone in the process of reuniting.
Careening is the operation of heaving down a ship on one side, in order to expose the other side for cleaning.
Cartel. A written agreement between belligerents for an exchange of prisoners.
Caulk. To make a ship's seams watertight by plugging the crevices with oakum (i.e. old untwisted rope).
Chasers. Bow-chasers were two long chase-guns placed forward in the bow ports to fire directly ahead. Stern-chasers were similar guns mounted astern.
Clean. A clean ship is one whose bottom is free from barnacles and weed that check the pace.
Clearing for action. To get ready for battle by clearing the decks from encumbrances and anything unnecessary or dangerous, such as wooden partitions between cabins, etc.
Cochineal. A dye stuff consisting of female cochineal insects killed and dried by heat. They yield a brilliant scarlet dye.