- Disorder of cardiac rhythm characterized by rapid, irregular atrial impulses and ineffective atrial contractions.
Definition from: MeSH via Unified Medical Language System at the National Library of Medicine
- Very rapid uncoordinated contractions of the atria of the heart resulting in a lack of synchronism between heartbeat and pulse beat -- called also auricular fibrillation.
Definition from: Merriam-Webster's Medical Dictionary by Merriam-Webster Inc.
See also Understanding Medical Terminology.