n.
Pronunciation: ' fer-m ē - ˌ än, ' f ə r-
Function: noun
Etymology: Enrico Fermi + English 2 -on
Date: 1947
: a particle (as an electron, proton, or neutron) whose spin quantum number is an odd multiple of 1/2 ― compare BOSON
– fer · mi · on · ic \ ˌ fer-m ē - ' ä-nik, ˌ f ə r- \ adjective