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

Grid Dynamics says the platform has delivered measurable gains, including inspection cycles up to 1,000 times faster and anomaly detection 24 times quicker in industrial deployments. — Jijo Malayil, Interesting Engineering, 17 July 2026

Machine learning models trained on clinical data can identify patterns and anomalies much faster than humans. — Subba Rao Katragadda, Forbes.com, 17 July 2026

Scientists are more certain that honeybees are magnetoreceptive – researchers have even trained them to discriminate between local magnetic anomalies. — Laura Russo, The Conversation, 17 July 2026

These two ocean anomalies may look opposite on the map, but their atmospheric impact is pushing in the same direction, creating an atmospheric shield for the United States hurricane season. — Doyle Rice, USA Today, 17 July 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

Podcast

Get Word of the Day delivered to your inbox!

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