Look up irregular or irregularity in Wiktionary, the free dictionary.
9 See also,
Something that is irregular does not follow the expected pattern. The term is used in many different fields, with various meanings.
Irregular inflection, the formation of derived forms such as plurals in unpredictable ways
In canon law, an irregularity is an impediment for the Catholic priesthood or for exercising orders already received,
Irregularity of a surface,
Irregularity of distributions,
Irregularity in shapes,
Constipation, also called "irregularity",
Irregular menstrual cycle,
Irregular chess opening