irregular
Pronunciation: /ɪˈrɛgjʊlə/
adjective
- 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.
noun
(usually irregulars)
Origin:
late Middle English (in the sense 'not conforming to rule (especially that of the Church')): via Old French from medieval Latin irregularis, from in- 'not' + regularis (see regular)

Spelling help
Spell irregular and the related word irregularity with a double r at the beginning.