from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Contrary to rule, accepted order, or general practice.
  • adjective Not conforming to legality, moral law, or social convention.
  • adjective Not straight, uniform, or symmetrical.
  • adjective Of uneven rate, occurrence, or duration.
  • adjective Deviating from a type; atypical.
  • adjective Botany Having differing floral parts, as of a zygomorphic or asymmetric flower.
  • adjective Falling below the manufacturer's standard or usual specifications; imperfect.
  • adjective Grammar Departing from the usual pattern of inflection, derivation, or word formation, as the present forms of the verb be or the plural noun children.
  • adjective Not belonging to a permanent, organized military force.
  • noun One, such as an item of merchandise, that is irregular.
  • noun A soldier, such as a guerrilla, who is not a member of a regular military force.

from The Century Dictionary.

  • Not regular; lacking regularity or method in some respect; not conformable to rule, order, symmetry, uniformity, or a fixed principle; deviating from the normal or usual course or state; devious; unmethodical; uneven: as, an irregular figure, outline, or surface; irregular verbs; irregular troops.
  • Not regular in action or method; not conformed or conforming to regular rules or principles; hence, disorderly; lawless; improper: as, he is given to irregular courses.
  • Specifically In human anatomy, being of no determinate shape, as a vertebra: said only of bones.
  • In zoology: Not having a definite form; bilaterally or radially unsymmetrical; not having the form usual in a group; differing in an unusual manner from neighboring parts: as, an irregular third joint of an insect's antenna.
  • Not arranged in a definite manner, or varying in position or direction: as, irregular marks (that is, marks varying in size or distance from one another); irregular punctures or striæ.
  • In echinoderms, not exhibiting radial symmetry; exocyclic or petalostichous; spatangoid or clypeastroid: specifically said of the heart-urchins and other sea-urchins of the division Irregularia. See cut under petalostichous.
  • In botany, not having all the members of the same part alike: said of flowers.
  • noun One who is not subject or does not conform to established regulations; especially, a soldier who is not in regular service, or a person practising medicine without belonging to the regular profession.

from the GNU version of the Collaborative International Dictionary of English.

  • noun One who is not regular; especially, a soldier not in regular service.
  • adjective Not regular; not conforming to a law, method, or usage recognized as the general rule; not according to common form; not conformable to nature, to the rules of moral rectitude, or to established principles; not normal; unnatural; immethodical; unsymmetrical; erratic; no straight; not uniform

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Nonstandard; not conforming to rules or expectations.
  • adjective Of a surface, rough.
  • noun A soldier who is not a member of an official military force and, often, does not follow regular army tactics.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective independent in behavior or thought
  • adjective (used of the military) not belonging to or engaged in by regular army forces
  • adjective lacking continuity or regularity
  • adjective falling below the manufacturer's standard
  • adjective (of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
  • adjective (of a surface or shape); not level or flat or symmetrical
  • noun a member of an irregular armed force that fights a stronger force by sabotage and harassment
  • adjective deviating from normal expectations; somewhat odd, strange, or abnormal
  • adjective not occurring at expected times
  • noun merchandise that has imperfections; usually sold at a reduced price without the brand name
  • adjective contrary to rule or accepted order or general practice


from Wiktionary, Creative Commons Attribution/Share-Alike License

From Old French irreguler, from Medieval Latin irregularis, from in- + regularis.


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  • I don't have a list to add this word to, but I came across a vaguely amusing usage today:

    "Very early in their recapitulation of the imperfect subjunctive of the irregular verb stare Mrs Fielding saw with alarm that her pupil's conduct was likely to grow even more irregular than her verb."

    --Patrick O'Brian, Treason's Harbour, 63-64

    February 15, 2008

  • Haha!

    February 15, 2008