Anion \An"i*on\, n. [Gr. ?, neut. ?, p. pr. of ? to go up; ? up + ? to go.]

(Chem.) An electro-negative element, or the element which, in electro-chemical decompositions, is evolved at the anode; -- opposed to cation. --Faraday.

Source: Webster's Revised Unabridged Dictionary (1913)