Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


noun, anom·a·ly \ə-ˈnä-mə-lē\

Simple Definition of anomaly

  • : something that is unusual or unexpected : something anomalous

Source: Merriam-Webster's Learner's Dictionary

Full Definition of anomaly

plural anomalies

  1. 1 :  the angular distance of a planet from its perihelion as seen from the sun

  2. 2 :  deviation from the common rule :  irregularity

  3. 3 :  something anomalous :  something different, abnormal, peculiar, or not easily classified

Examples of anomaly in a sentence

  1. 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

  2. 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

  3. 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

  4. 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

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

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

Origin of anomaly

(see anomalous)

First Known Use: 1603

ANOMALY Defined for Kids


noun anom·a·ly \ə-ˈnä-mə-lē\

Definition of anomaly for Students

plural anomalies

  1. :  something different, abnormal, strange, or not easily described

Medical Dictionary


noun anom·a·ly \ə-ˈnäm-ə-lē\

Medical Definition of anomaly

plural anomalies

  1. :  a deviation from normal especially of a bodily part <the infants demonstrated congenital anomalies> <personality anomalies>

Seen and Heard

What made you want to look up anomaly? Please tell us where you read or heard it (including the quote, if possible).


to dishevel or rumple

Get Word of the Day daily email!


Take a 3-minute break and test your skills!


Which of these is a synonym of nonplus?

reduce disapprove soothe perplex
Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.