[zee-ner] 
| a semiconductor diode across which the reverse voltage remains almost constant over a wide range of currents, used esp. to regulate voltage. |
| ze·ner diode or Ze·ner diode (zē'nər) n. A silicon semiconductor device used as a voltage regulator because of its ability to maintain an almost constant voltage with a wide range of currents. [After Clarence Melvin Zener (1905-1993), American physicist.] |