ammonium

am·mo·ni·um   (ə-mō'nē-əm)    n.  The univalent chemical ion NH4+, derived from ammonia, whose compounds chemically resemble the alkali metals. [ammon(ia) + -ium.]

Main Entry: am·mo·ni·um
Pronunciation: &-'mO-nE-&m
Function: noun
: an ion NH₄⁺derived from ammonia bycombination with a hydrogen ion and known in organic compounds (as quaternary ammonium compounds) and in compounds (as salts) that resemble in properties the compounds of the alkali metals

ammonium am·mo·ni·um (ə-mō'nē-əm)
n.
The univalent radical NH₄+, that is derived from ammonia and that reacts as a univalent metal in forming ammonium compounds.

ammonium   (ə-mō'nē-əm)  Pronunciation Key  A positively charged ion, NH4, derived from ammonia and found in a wide variety of organic and inorganic compounds. Compounds of ammonium chemically resemble the alkali metals.