GNU Collaborative International Dictionary of English

Found one definition

1.       
   Anion (), n. [Gr. , neut. , p. pr. of  to go up;  up +  to go.] (Chem.) An electro-negative atom or group of atoms, or the element which, in electro-chemical decompositions, is evolved at the anode; -- opposed to cation.  Faraday.
   
   [1913 Webster]