Meaning of ION in English

ION

i ‧ on /ˈaɪən $ ˈaɪən, ˈaɪɑːn/ BrE AmE noun [countable] technical

[ Date: 1800-1900 ; Language: Greek ; Origin: present participle of ienai 'to go' ]

an atom which has been given a positive or negative force by adding or taking away an ↑ electron ⇨ proton

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.