onium

1 of 2

adjective

oni·​um ˈō-nē-əm 

: being or characterized by a usually complex cation

-onium

2 of 2

noun suffix

: an ion having a positive charge

hydronium

compare -ium sense 1b

Word History

Etymology

Adjective

-onium

Noun suffix

New Latin, from ammonium

First Known Use

Adjective

1905, in the meaning defined above

Medical Definition

onium

adjective

oni·​um ˈō-nē-əm 

: being or characterized by a usually complex cation

onium salts