Dictionary
am•mo•ni•um
Pronunciation: (u-mō'nē-um), [key]—
n. Chem.
the univalent ion, NH
4+, or group, NH
4, which plays the part of a metal in the salt formed when ammonia reacts with an acid.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.