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; as, an irregular line; an irregular figure; an irregular verse; an irregular physician; an irregular proceeding; irregular motion; irregular conduct, etc. Cf. Regular.
- Contrary to rule, accepted order, or general practice: irregular hiring practices.
- Not conforming to legality, moral law, or social convention: an irregular marriage.
- Not straight, uniform, or symmetrical: irregular facial features.
- Of uneven rate, occurrence, or duration: an irregular heartbeat.
- Deviating from a type; atypical.
- Botany Having differing floral parts, as of a zygomorphic or asymmetrical flower.
- Falling below the manufacturer's standard or usual specifications; imperfect.
- 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.
- Not belonging to a permanent, organized military force: irregular troops.
- One, such as an item of merchandise, that is irregular.
- A soldier, such as a guerrilla, who is not a member of a regular military force.