indicating a metallic element: platinum, barium (in chemistry) indicating groups forming positive ions: ammonium chloride, hydroxonium ion indicating a biological structure: syncytium
WordReference Random House Unabridged Dictionary of American English © 2025
-ium,
- a suffix found on nouns borrowed from Latin, esp. derivatives of verbs (odium;
tedium;
colloquium;
delirium), deverbal compounds with the initial element denoting the object of the verb (nasturtium), other types of compounds (equilibrium;
millennium), and derivatives of personal nouns, often denoting the associated status or office (collegium;
consortium;
magisterium);
-ium also occurs in scientific coinages on a Latin model, as in names of metallic elements (barium;
titanium) and as a Latinization of Gk -ion (pericardium).
- Neo-Latin, Latin, neuter suffix
Collins Concise English Dictionary © HarperCollins Publishers::
'-ium' also found in these entries (note: many are not synonyms or translations):
achene
- actinium
- actinium emanation
- actinium series
- adage
- adultery
- adverb
- aecium
- aethalium
- allodium
- alluvium
- allyl
- aluminum
- americium
- ammonal
- ammonium
- androclinium
- antependium
- anthodium
- anthurium
- apterium
- aquarist
- archegonium
- armistice
- artifice
- augury
- auspice
- baric
- barite
- barium
- barium bromate
- barium carbonate
- barium chloride
- barium chromate
- barium enema
- barium hydroxide
- barium oxide
- barium peroxide
- barium stearate
- barium sulfate
- barium sulfide
- barium thiosulfate
- barium titanate
- barium x-ray
- barium yellow
- barouche
- basidium
- benefice
- berkelium
- beryllium