anomaly

noun

anom·​a·​ly ə-ˈnä-mə-lē 

plural anomalies

1

: something different, abnormal, peculiar, or not easily classified : something anomalous

They regarded the test results as an anomaly.

2

: deviation from the common rule : irregularity

3

: the angular distance of a planet from its perihelion as seen from the sun

Did you know?

You might be familiar with the Greek word homos, which means “same.” It is from this word that we get words like homonym, homogeneous, and homophone, all of which have to do with sameness or similarity. What does this have to do with anomaly? Although it’s not obvious, homos is a part of the etymology of anomaly, too. Anomaly is a descendant—by way of Latin and Middle French—of the Greek word anṓmalos, which means “uneven” or “irregular.” Anṓmalos comes from the prefix a- (meaning “not”) and the word homalόs (meaning “even”)—and homalόs comes from homos.

Synonyms of anomaly

• exception
• abnormality
• rarity

Examples of anomaly in a Sentence

In approximately 10% of patients, autism can be explained by genetic syndromes and known chromosomal anomalies (most of which have recognizable features in addition to autism) … —Lauren A. Weiss et al., New England Journal of Medicine, 14 Feb. 2008

Eleven minutes may not sound like much when you're waiting for a table at your favorite restaurant, but in the course of centuries, eleven minutes and change become a formidable chunk of time. By the 1300s, those superfluous minutes had added up to hours, then days, then more than a week. The calendar was losing time, irrevocably, to the "real" year, slipping further and further behind in its measurement of the earth's orbit. Anomalies began to creep into what had been the certainties of life. The spring equinox—one of two moments in the year when day and night are of equal length all over the earth, and which occurs on or about March 21—began to fall on March 16, then 15, then 14. —Michelle Stacey, Harper's, December 2006

Californians aren't the only ones vexed by rolling brownouts and other power-supply anomalies. Everyday power spikes, surges, sags, and line noise cause computers, stereo equipment, televisions, telephones, and other delicate electronic equipment to go psychotic or have complete nervous breakdowns. —Fortune, 25 June 2001

This policy may well have made sense back when steroid use was an anomaly. Now that bulking up with chemical help seems to be more popular than ever, it's incumbent on baseball to take action. —Steve Kettman, New York Times, 20 Aug. 2000

We couldn't explain the anomalies in the test results.

her C grade is an anomaly, as she's never made anything except A's and B's before

Recent Examples on the Web

These massive fire weather systems, once an anomaly only seen over volcanoes, did not enter the vocabulary of fire scientists until the late 1990s, when atmospheric CO2 reached 370 parts per million (ppm)—about 30% higher than pre-industrial levels. — John Vaillant, Time, 8 Aug. 2026

The update was published 10 weeks after the hot fire test anomaly, and in parallel Blue Origin has rapidly been working to clear debris around the sprawling Launch Complex 36-A site in Florida and starting to rebuild a launch tower. — Eric Berger, ArsTechnica, 6 Aug. 2026

Used well, these tools can reduce manual reporting, improve forecasting, identify anomalies and help teams focus on higher-value decisions. — Ozan Ozerk, Forbes.com, 6 Aug. 2026

Economists will be looking to see if that trend was a statistical anomaly produced by seasonal and other distortions, or a more serious sign of deeper trouble in a labor economy marked by companies generally slow to hire as well as slow to fire. — Jeff Cox, CNBC, 6 Aug. 2026

Word History

Etymology

borrowed from Middle French and Latin; Middle French anomalie "irregularity in grammar," borrowed from Latin anōmalia, borrowed from Greek anōmalía "unevenness, inequality, inconsistency," from anṓmalos "not uniform, unequal, inconsistent, anomalous" + -ia -y entry 2

First Known Use

1585, in the meaning defined at sense 2

Rhymes for anomaly

• homily

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Kids Definition

anomaly

noun

anom·​a·​ly ə-ˈnäm-ə-lē 

plural anomalies

1

: an act or instance of not following the general rule or method

2

: something anomalous : something different, abnormal, strange, or not easily described

Medical Definition

anomaly

noun

anom·​a·​ly ə-ˈnäm-ə-lē 

plural anomalies

: a deviation from normal especially of a bodily part

the infants demonstrated congenital anomalies

personality anomalies