<p><strong>Adjective</strong></p><ul><li>without symmetry, even shape, formal arrangement, etc.: an irregular pattern</li><li>not characterized by any fixed principle, method, continuity, or rate: irregular intervals</li><li>not conforming to established rules, customs, etiquette, morality, etc.: highly irregular behavior</li><li>not according to rule, or to the accepted principle, method, course, order, etc.</li><li>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</li><li>Military: (formerly, of troops) not belonging to an organized group of the established forces</li><li>flawed, damaged, or failing to meet a specific standard of manufacture: a sale of irregular shirts</li><li>Botany: not uniform</li><li>(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</li><li>deviating or experiencing deviations from a normally regular or cyclic body function, as bowel habits or menstruation</li><li>(of a stock or commodity market) of mixed market activity; showing no clear up or down trend</li></ul><p><strong>Noun</strong></p><ul><li>a person or thing that is irregular</li><li>Commerce: a product or material that does not meet specifications or standards of the manufacturer, as one having imperfections in its pattern</li><li>Military: a soldier or combatant not of a regular military force, as a guerrilla or partisan</li></ul>