Barnacle
Barnacle turns up in 2 fields: PCBs, maritime. Here is what it means to the people in each one.
Barnacle in PCBs
An unplanned component or wire soldered onto a board to fix a design error.
A component, such as a resistor, capacitor, or jumper wire, tacked onto a printed circuit board after initial assembly to correct a mistake or modify a circuit. These modifications are typically soldered directly to pins, vias, or scraped traces rather than proper pads. They are common during the bring-up phase of a prototype but are not acceptable in final production hardware.
"The regulator was oscillating, so I had to add a barnacle capacitor across the output pins to stabilize it."
Barnacle in maritime
A hard-shelled marine crustacean that attaches itself to the underwater hull of a vessel.
These marine organisms cement themselves to submerged surfaces and form dense, rocky colonies. On a ship's hull, they create significant hydrodynamic drag, which reduces speed and drastically increases fuel consumption. Drydock crews must scrape or blast them off during maintenance, and shipbuilders apply toxic or ablative anti-fouling paints to prevent their attachment.
"She's running slow and burning too much heavy fuel, so we need to get her out of the water and scrape the barnacles off."