atrial fibrillation atrial auricle • atrial septal defect · · · Info · Definitions · Characters · · atrial fibrillation · · Text Common · · Latin · · Scripts 19 · · Length 6 · · Syllables Definitions · · · (noun) fibrillation of the muscles of the atria of the heart. Synonyms: atrial fibrillation. · · Noun Definition 1 Characters · · space U+0020 a latin small letter a U+0061 b latin small letter b U+0062 f latin small letter f U+0066 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 t latin small letter t U+0074