noun A marine crustacean of the subclass Cirripedia that attaches itself to submerged surfaces such as tidal rocks or the bottoms of ships.
noun The barnacle goose.
noun In electrical engineering, a change made to a product on the manufacturing floor that was not part of the original product design.
noun On printed circuit boards, a change such as soldering a wire in order to connect two points, or addition such as an added resistor or capacitor, subassembly or daughterboard.
noun A deprecated or obsolete file, image or other artifact that remains with a project even though it is no longer needed.
(The addition of quotations indicative of this usage is being sought:)
noun An instrument like a pair of pincers, to fix on the nose of a vicious horse while shoeing so as to make it more tractable.