Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.

Definition of Anion

Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026

Anion: A negatively charged ion. Pronounced an-I-on.

An anion is as opposed to a cation, which is a positively charged ion.

Need Expert Advice on Your Condition?

Get a personalized video breakdown and treatment plan from our senior neurosurgeons using your MRI/CT scans.

👉 Request MRI Review