noun, na-adjective
anomaly; abnormality; irregularity
Refers to something that deviates from the normal or expected state. Often used in formal or technical contexts.
このデータには不正常な値が含まれている。
This data contains anomalous values.
彼の行動は不正常だ。
His behavior is abnormal.
正常 means 'normal' or 'regular', the opposite of 不正常.
Compound of 不 (fu, 'not') + 正常 (seijō, 'normal'). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for negation.