An Etymological Dictionary of Astronomy and Astrophysics

1. A conductor by means of which a current passes into or out of a medium. The positive electrode is called anode; the negative electrode is called cathode.
   
2. In a CCD detector, one of a series of parallel conducting plates which run across the device at right angles to the channels and subdivide a channel into pixels. The plates create an electric field within the semiconductor which therefore forms a storage site for photo-generated charges.

See also: Coined by E. physicist and chemist Michael Faraday (1791-1867) from electro-, → electric, + Gk. hodos “way.”