IRREG'ULAR, adjective [Latin irregularis; in and regularis, regula. See Regular.]
1. Not regular; not according to common form or rules; as an irregular building or fortification.
2. Not according to established principles or customs; deviating from usage; as the irregular proceedings of a legislative body.
3. Not conformable to nature or the usual operation of natural laws; as an irregular action of the heart and arteries.
4. Not according to the rules of art; immethodical; as irregular verse; an irregular discourse.
5. Not in conformity to laws, human or divine; deviating from the rules of moral rectitude; vicious; as irregular conduct or propensities.
6. Not straight; as an irregular line or course.
7. Not uniform; as irregular motion.
8. In grammar, an irregular noun or verb is one which deviates from the common rules in its inflections.
IRREG'ULAR, noun A soldier not in regular service.