Etymology: Middle English irreguler, from Anglo-French, from Late Latin irregularis not in accordance with rule, from Latin in- + regularis regular
Date: 14th century
a. not being or acting in accord with laws, rules, or established custom <irregular conduct> b. not conforming to the usual pattern of inflection <irregular verbs>; specifically strong 16 c. not following a usual or prescribed procedure; especially British celebrated without either proclamation of the banns or publication of intention to marry <irregular marriage> 2. not belonging to or a part of a regular organized group; specifically not belonging to a regular army but raised for a special purpose <irregular troops> 3. a. lacking perfect symmetry or evenness <an irregular coastline> b. having one or more floral parts of the same whorl different in size, shape, or arrangement; specifically zygomorphic 4. lacking continuity or regularity especially of occurrence or activity <irregular employment> • irregularly adverb Synonyms: irregular, anomalous, unnatural mean not conforming to rule, law, or custom. irregular implies not conforming to a law or regulation imposed for the sake of uniformity in method, practice, or conduct <concerned about his irregular behavior>. anomalous implies not conforming to what might be expected because of the class or type to which it belongs or the laws that govern its existence <her drive made her an anomalous figure in a sleepy organization>. unnatural suggests what is contrary to nature or to principles or standards felt to be essential to the well-being of civilized society <prisoners treated with unnatural cruelty>. II. noun Date: 15th century one that is irregular: as a. a soldier who is not a member of a regular military force b. plural merchandise that has minor defects or that falls next below the manufacturer's standard for firsts
New Collegiate Dictionary. 2001.