If events or actions occur at irregular intervals, the periods of time between them are of different lengths.

Something that is irregular is not smooth or straight, or does not form a regular pattern.

Irregular behaviour is dishonest or not in accordance with the normal rules.

An irregular verb, noun, or adjective has different forms from most other verbs, nouns, or adjectives in the language. For example, 'break' is an irregular verb because its past form is 'broke', not 'breaked'.

Irregular troops do not belong to an official national army.