anion (n.)

1834, coined from Greek anodos "way upward," from ano "upward," from ana "up" (see ana-) + hodos "a way," a word of uncertain origin (see Exodus). Proposed by the Rev. William Whewell, English polymath, and published by English chemist and physicist Michael Faraday. So called from the path the electrical current was thought to take. Compare cathode. Related: Anodic, anodal.

before vowels an-, word-forming element meaning: 1. "upward, up in place or time," 2. "back, backward, against," 3. "again, anew," from Greek ana (prep.) "up, on, upon; up to, toward; throughout; back, backwards; again, anew," from an extended form of PIE root *an- (1) "on, upon, above" (see on, which is the English cognate). In old medical prescriptions, ana by itself meant "an equal quantity of each."