1not even or balanced in shape or arrangement:his strong, irregular features occurring at uneven or varying rates or intervals:an irregular heartbeat Botany (of a flower) having the petals differing in size and shape; zygomorphic. 2contrary to the rules or to that which is normal or established:their involvement in irregular financial dealings (of troops) not belonging to regular or established army units.
3 Grammar (of a verb or other word) having inflections that do not conform to the usual rules.
1a member of an irregular military force.
chiefly North American an imperfect piece of merchandise sold at a reduced price.