irregular

From Middle English irreguler, from Old French irreguler, from Medieval Latin or Late Latin irrēgulāris, from in- + regularis, equivalent to ir- +‎ regular.

• (Received Pronunciation) IPA^(key): /ɪˈɹɛɡ.jʊ.lə/

  • Audio (Southern England):

    (file)

• (General American, Canada) IPA^(key): /ɪˈɹɛɡ.jə.lɚ/

  • Audio (Texas):

    (file)

• (Australia) IPA^(key): /ɪˈɹeɡ.jə.lə/
• (New Zealand) IPA^(key): /əˈɹeɡ.jə.lə/

irregular (comparative more irregular, superlative most irregular)

1. Nonstandard; not conforming to rules or expectations.
   • 1967, Barbara Sleigh, Jessamy, Sevenoaks, Kent: Bloomsbury, published 1993, →ISBN, page 33:

     ‘ “It would be most irregular Grandpa!” says Miss Cecily frowning and tapping her foot. “Well, we’re a pretty irregular family so that’s neither here nor there,” says the old man, impish like. [...] ’

2. Of a surface, rough.
3. Without symmetry, regularity, or uniformity.
   • 1944, Miles Burton, chapter 5, in The Three Corpse Trick:

     The hovel stood in the centre of what had once been a vegetable garden, but was now a patch of rank weeds. Surrounding this, almost like a zareba, was an irregular ring of gorse and brambles, an unclaimed vestige of the original common.

   • 1980, AA Book of British Villages, Drive Publications Ltd, page 100:

     Near by, where the crystal clear River Llugwy is crossed by a bridge, stands a small and ancient church built of massive, irregular boulders.

   • 2013 January 1, Paul Bartel, Ashli Moore, “Avian Migration: The Ultimate Red-Eye Flight”, in American Scientist, volume 101, number 1, pages 47–48:

     Many of these classic methods are still used, with some modern improvements. For example, with the aid of special microphones and automated sound detection software, ornithologists recently reported […] that pine siskins (Spinus pinus) undergo an irregular, nomadic type of nocturnal migration.

   • 2013 July 19, Ian Sample, “Irregular bedtimes may affect children's brains”, in The Guardian Weekly, volume 189, number 6, page 34:

     Irregular bedtimes may disrupt healthy brain development in young children, according to a study of intelligence and sleeping habits.  ¶ Going to bed at a different time each night affected girls more than boys, but both fared worse on mental tasks than children who had a set bedtime, researchers found.

   • 2019 October, Tony Miles, Philip Sherratt, “EMR kicks off new era”, in Modern Railways, page 58:

     The improvements will be most keenly felt across Lincolnshire, where current irregular service patterns are more a function of operational convenience than passenger demand.

4. (geometry) Of a polygon, not regular; having sides that are not equal or angles that are not equal.
5. (geometry) Of a polyhedron, whose faces are not all regular polygons (or are not equally inclined to each other).
6. (grammar) Of a word, not following the regular or expected patterns of inflection in a given language.

   "Calves", "cacti", and "children" are irregular plurals.

   "To buy" is an irregular English verb: its past simple and past participle tense is "bought".

   I hate learning all the irregular conjugations in French.

7. (gastroenterology) Having abnormal bowel movements at inconsistent intervals.

   Antonym: regular

• (nonstandard): abnormal, singular; see also Thesaurus:strange
• (rough): coarse, salebrous; see also Thesaurus:rough
• (without uniformity): unstable, unsteady; see also Thesaurus:unsteady
• (not following the regular patterns of inflection): heteroclite

• regular

irregular (plural irregulars)

1. A soldier who is not a member of an official military force and who may not use regular army tactics.
2. One who does not regularly attend a venue.
   • 2015, Brian Cook, Hands Across The Sea, page 190:

     There's one neighborhood tavern where the regulars and irregulars go after a hard day to unlax and rewind, throw back a few, and just hang out - you know the one.

• Baker Street Irregular

Learned borrowing from Late Latin irrēgulāris.

• IPA^(key): (Northern, Central) [i.rə.ɣuˈlar]
• IPA^(key): (Balearic) [i.rə.ɣuˈla]
• IPA^(key): (Valencia) [i.re.ɣuˈlaɾ]
• IPA^(key): (Northwestern) [i.re.ɣuˈlar]

• Audio (Barcelona):

  (file)

• Rhymes: -aɾ

irregular m or f (masculine and feminine plural irregulars)

1. irregular

   Antonym: regular

• irregularment

• irregularitat

• “irregular”, in Diccionari de la llengua catalana [Dictionary of the Catalan Language] (in Catalan), second edition, Institute of Catalan Studies [Catalan: Institut d'Estudis Catalans], April 2007
• “irregular”, in Gran Diccionari de la Llengua Catalana, Grup Enciclopèdia Catalana, 2026
• “irregular” in Diccionari normatiu valencià, Acadèmia Valenciana de la Llengua.
• Alcover, Antoni Maria; Moll, Francesc de Borja (1963), “irregular”, in Diccionari català-valencià-balear (in Catalan)

Attested since circa 1300. Borrowed from Late Latin irrēgulāris.

• Rhymes: -aɾ
• Hyphenation: i‧rre‧gu‧lar

irregular m or f (plural irregulares)

1. irregular

   Antonym: regular

• irregularidade

• Seoane, Ernesto Xosé González; Granja, María Álvarez de la; Agrelo, Ana Isabel Boullón (2006–2022), “yrregular”, in Dicionario de Dicionarios do galego medieval [Dictionary of dictionaries of Medieval Galician] (in Galician), Santiago de Compostela: Instituto da Lingua Galega
• Barreiro, Xavier Varela; Guinovart, Xavier Gómez (2006–2018), “irregular”, in Corpus Xelmírez: corpus lingüístico da Galicia medieval [Corpus Xelmírez: linguistic corpus of Medieval Galicia] (in Galician), Santiago de Compostela: Instituto da Lingua Galega
• Antón Santamarina, editor (2006–2013), “irregular”, in Dicionario de Dicionarios da lingua galega [Dictionary of Dictionaries of the Galician language] (in Galician), Santiago de Compostela: Instituto da Lingua Galega
• Antón Santamarina, Ernesto X. González Seoane, María Álvarez de la Granja, editors (2003–2018), “irregular”, in Tesouro informatizado da lingua galega (in Galician), Santiago de Compostela: Instituto da Lingua Galega

• “irregular”, in Dicionario da Real Academia Galega (in Galician), A Coruña: Royal Galician Academy, 2012–2026
• “irregular”, in Dicionário Estraviz de galego (in Galician), 2014–2026

Learned borrowing from Late Latin irrēgulāris.

irregular m or f (plural irregulares)

1. irregular; nonstandard
2. (grammar) irregular (not following an inflectional paradigm)

• regular

• irregularmente

• irregularidade

• “irregular”, in Dicionário Priberam da Língua Portuguesa (in Portuguese), Lisbon: Priberam, 2008–2026

Learned borrowing from Late Latin irrēgulāris.

• IPA^(key): /ireɡuˈlaɾ/ [i.re.ɣ̞uˈlaɾ]
• Rhymes: -aɾ
• Syllabification: i‧rre‧gu‧lar

irregular m or f (masculine and feminine plural irregulares)

1. irregular, uneven, erratic, haphazard
2. patchy, spotty, jagged, ragged
3. fitful
4. (grammar) (of a verb etc.) irregular

   Antonym: regular

• “irregular”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8.1, Royal Spanish Academy [Spanish: Real Academia Española], 15 December 2025