n.
Pronunciation: ' ī - ə n, ' ī - ˌ än
Function: noun
Etymology: Greek, neuter of i ō n, present participle of ienai to go ― more at ISSUE
Date: circa 1834
1 : an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons
2 : a charged subatomic particle (as a free electron)