|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|Compare cation a negatively charged ion; an ion that is attracted to the anode during electrolysis|
|[C19: from |
anion an·i·on (ān'ī'ən)
A negatively charged ion, especially one that migrates to the anode in electrolysis.