irregular

[ih-reg-yuh-ler]

adjective

1. without symmetry, even shape, formal arrangement, etc..

   an irregular pattern.

   Synonyms: uneven, unsymmetrical

2. not characterized by any fixed principle, method, continuity, or rate.

   irregular intervals.

   Synonyms: lawless, eccentric, erratic, capricious, disorderly, unsystematic, unmethodical

3. not conforming to established rules, customs, etiquette, morality, etc..

   highly irregular behavior.

4. not according to rule, or to the accepted principle, method, course, order, etc.

   Synonyms: unusual, anomalous

5. Grammar.,  not conforming to the prevalent pattern or patterns of formation, inflection, construction, etc., of a language; having a rule descriptive of a very small number of items.

   The English verbs “keep” and “see” are irregular in their inflections.

6. Military.,  (formerly, of troops) not belonging to an organized group of the established forces.

7. flawed, damaged, or failing to meet a specific standard of manufacture.

   a sale of irregular shirts.

8. Botany.

   1. not uniform.

   2. (of a flower) having the members of some or all of its floral circles or whorls differing from one another in size or shape, or extent of union.

9. deviating or experiencing deviations from a normally regular or cyclic body function, as bowel habits or menstruation.

10. (of a stock or commodity market) of mixed market activity; showing no clear up or down trend.

noun

1. a person or thing that is irregular.

2. Commerce.,  a product or material that does not meet specifications or standards of the manufacturer, as one having imperfections in its pattern.

3. Military.,  a soldier or combatant not of a regular military force, as a guerrilla or partisan.

irregular

/ ɪˈrɛɡjʊlə /

adjective

1. lacking uniformity or symmetry; uneven in shape, position, arrangement, etc

2. not occurring at expected or equal intervals

   an irregular pulse

3. differing from the normal or accepted practice or routine

4. not according to established standards of behaviour; unconventional

5. (of the formation, inflections, or derivations of a word) not following the usual pattern of formation in a language, as English plurals ending other than in -s or -es

6. of or relating to guerrillas or volunteers not belonging to regular forces

   irregular troops

7. (of flowers) having any of their parts, esp petals, differing in size, shape, etc; asymmetric

8. (of merchandise) not up to the manufacturer's standards or specifications; flawed; imperfect

noun

1. a soldier not in a regular army

2. (often plural) imperfect or flawed merchandise Compare second 1

Other Word Forms

• irregularly adverb
• quasi-irregular adjective
• quasi-irregularly adverb

Word History and Origins

Origin of irregular¹

First recorded in 1350–1400; from Late Latin irrēgulāris ( ir- ², regular ); replacing Middle English irreguler, from Middle French

Synonym Study

Irregular, abnormal, exceptional imply a deviation from the regular, the normal, the ordinary, or the usual. Irregular, not according to rule, refers to any deviation, as in form, arrangement, action, and the like; it may imply such deviation as a mere fact, or as regrettable, or even censurable. Abnormal means a deviation from the common rule, often implying that this results in an aberrant or regrettably strange form or nature of a thing: abnormal lack of emotion; A two-headed calf is abnormal. Exceptional means out of the ordinary or unusual; it may refer merely to the rarity of occurrence, or to the superiority of quality: an exceptional case; an exceptional mind. Because of the stigma of abnormal, exceptional is today frequently substituted for it in contexts where such a euphemism may be thought to be appropriate: a school for exceptional children (children who are abnormal in behavior, mental capacity, or the like).

Example Sentences

Libyan authorities said in July there were up to four million irregular migrants in the country.

Read more on Barron's

They will point out—and they love to point this out—that legalization has brought sunlight to an underground activity and allowed authorities to detect irregular betting patterns and catch offenders.

Read more on The Wall Street Journal

The UK government said 16 irregular migrants were sent to France this week under the deal, bringing the total number of returns over two months to 42.

Read more on Barron's

During the Covid pandemic, anticorruption officials say hundreds of millions of dollars in irregular procurement tenders were awarded, including to a company linked to family members of the health minister at the time.

Read more on The Wall Street Journal

Atrial fibrillation is of particular concern because it causes irregular heartbeats and erratic blood flow, raising the risk of blood clots and stroke.

Read more on Science Daily

Related Words

• capricious 
• erratic 
• intermittent 
• jerky 
• sporadic 
• uneven 
• unreliable