noun

• (electricity) An electrode, of a cell or other electrically polarized device, through which a positive current of electricity flows outwards (and thus, electrons flow inwards). It can have either a negative or a positive voltage with respect to anode of the same polarized device (depending on whether the device is a load or a source, respectively).
• (by extension) The electrode at which chemical reduction of cations takes place, usually resulting in the deposition of metal onto the electrode.
• (electronics) The electrode from which electrons are emitted into a vacuum tube or gas-filled tube.
• (electronics) That electrode of a semiconductor device which is connected to the n-type material of a p-n junction.