n.
Pronunciation: ' nü-kl ē - ˌ än, ' nyü-
Function: noun
Etymology: International Scientific Vocabulary
Date: 1923
1 : a proton or neutron especially in the atomic nucleus
2 : a hypothetical single entity with one-half unit of isospin that can manifest itself as either a proton or a neutron
– nu · cle · on · ic \ ˌ nü-kl ē - ' ä-nik, ˌ nyü- \ adjective