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1. Contrary to rule, accepted order, or general practice: irregular hiring practices.
2. Not conforming to legality, moral law, or social convention: an irregular marriage.
3. Not straight, uniform, or symmetrical: irregular facial features.
4. Of uneven rate, occurrence, or duration: an irregular heartbeat.
5. Deviating from a type; atypical.
6. Botany Having differing floral parts, as of a zygomorphic or asymmetric flower.
7. Falling below the manufacturer's standard or usual specifications; imperfect.
8. 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.
9. Not belonging to a permanent, organized military force: irregular troops.
1. One, such as an item of merchandise, that is irregular.
2. A soldier, such as a guerrilla, who is not a member of a regular military force.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.