-iums

Suffix (1)

-ium (noun-forming suffix, usually uncountable, plural -iums)

1. (usually) Used to form the names of metal elements, after the style of early-named elements, as well as the isotopes of hydrogen.
2. (usually) Used to form the temporary systematic element name of a metallic or nonmetallic element which is postulated to exist, or which has been newly synthesized and has not yet been assigned a permanent name.
3. (usually) Used to form the name of polyatomic cations. Common examples are quaternary ammonium compounds used as neuromuscular blocking agents, cholinergic agents, anticholinergic agents, antibacterials/antiseptics, or other agents.
   • Alternative form: -onium
4. (broadly, humorous, usually) Appended to common words to create scientific-sounding or humorous-sounding fictional substance names.
   • According to the FAQ, a site's coolness can be attributed to a trace element called coolium.1997, Bryan Pfaffenberger, Official Microsoft Internet Explorer 4 book, page 34

Suffix (2)

-ium (noun-forming suffix, plural -iums or -ia)

1. Used to form the name of an aggregation or mass of something, such as biological tissue
   • epithelium, pollinium
2. Forms the name of biological structures and parts.
   • clinanthium, periodontium

See all 7 meanings of -ium