from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A four-element electron tube containing an anode, cathode, control grid, and additional electrode.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A thermionic valve similar to a triode with the addition of a screen grid to protect the control grid
- n. A dynatron
from The Century Dictionary and Cyclopedia
- n. Among the sponge-spicules, one with four equal rays in the same plane.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a thermionic tube having four electrodes
Sorry, no etymologies found.