Anomaly

wiktionary

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From Latin anomalia, from Ancient Greek ἀνωμαλία(anōmalía, “irregularity, anomaly”), from ἀνώμαλος(anṓmalos, “irregular, uneven”), negating the meaning of ὁμαλός(homalós, “even”), from ὁμός(homós, “same”).

etymonline

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anomaly (n.)

1570s, "unevenness;" 1660s, "deviation from the common rule," from Latin anomalia, from Greek anomalia "inequality," abstract noun from anomalos "uneven, irregular," from an- "not" (see an- (1)) + homalos "even," from homos "same" (from PIE root *sem- (1) "one; as one, together with"). From 1722 as "something abnormal or irregular."