Very dense matter consisting of free neutrons, thought to exist in the interior of neutron stars where electrons and protons combine with each other as a result of extreme pressure.
Origin
1930s. From neutron + -ium, after German Neutronium.
Definition of neutronium in US English:
neutronium
nounnjuːˈtrəʊnɪəm
Science Fiction Astronomy
Very dense matter consisting of free neutrons, thought to exist in the interior of neutron stars where electrons and protons combine with each other as a result of extreme pressure.
Origin
1930s. From neutron + -ium, after German Neutronium.