What does "neutronium" mean?

A material composed entirely of neutrons.

What is a synonym for "neutronium"?

Common synonyms include: electron degenerate matter, element 0, element 0, element zero, n, n (nilium).

Neutronium

noun

noun ·Uncommon ·Advanced level

Definitions

Noun

1
A material composed entirely of neutrons. uncountable
2
A hypothetical gravitationally bound system of a neutron and an antineutron (the onium of a neutron), not predicted to exist under normal circumstances. uncountable

Synonyms

All synonyms

electron degenerate matter element 0 element 0 element zero n n (nilium)

Antonyms

All antonyms

antielement 0 antielement zero antineutrium antineutronium

Etymology

From neutron + -ium. Coined by scientist Andreas von Antropoff in 1926 (before the discovery of the neutron in 1931; neutrons had been predicted to exist in 1920).

Related phrases

neutron star

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.