Cathode

1. The electrode in an electrochemical cell toward which cations are drawn and where reduction occurs.
2. The negatively charged electrode in a vacuum tube.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

Cath"ode (?), n. [Gr. descent; down + way.] Physics

The part of a voltaic battery by which the electric current leaves substances through which it passes, or the surface at which the electric current passes out of the electrolyte; the negative pole; -- opposed to anode.

Faraday.

Cathode ray Phys., a kind of ray generated at the cathode in a vacuum tube, by the electrical discharge.

© Webster 1913.