Dictionary:

irregularity

  (ĭ-rĕg'yə-lăr'ĭ-tē)

1. The quality or state of being irregular.
2. Something irregular: found the firm's books riddled with irregularities.
3. Constipation.

noun

1. Lack of smoothness or regularity: asymmetry, crookedness, inequality, jaggedness, roughness, unevenness. See smooth/rough, straight/bent.
2. The condition of being abnormal: aberrance, aberrancy, aberration, abnormality, anomaly, deviance, deviancy, deviation, preternaturalness, unnaturalness. See good/bad, usual/unusual.

A defect, failure, or mistake in a legal proceeding or lawsuit; a departure from a prescribed rule or regulation.

An irregularity is not an unlawful act, however, in certain instances, it is sufficiently serious to render a lawsuit invalid. For example, a number of states have statutes that require the appointment of a guardian to represent the interests of a child who is being sued. The failure to do so is an irregularity that can be used as a ground for invalidating and setting aside a judgment entered against the child.

In other cases, however, the flaw might be a simple harmless error that can be easily rectified, and, therefore, does not render the proceeding invalid.

1) Can refer to any violation of house rules, regardless of intentionality, such as folding out of turn or bottom dealing.
2) Anything that might cause a flawed deck such as ear cards or unintentional marks that would distinguish them from other cards.

SoundPoker Says: 1) An irregularity of play can result in anything from a verbal warning to being banned from a gambling establishment.
2) If a dealer sees any marks or bends on any of the cards they will immediately discard of that deck and get a new one. A player also is within their rights to request that a new deck be used if they also notice any irregularities in a deck.

See Also: Ear, Foul Hand

The noun has 4 meanings:

Meaning #1: behavior that breaches the rule or etiquette or custom or morality
  Synonym: abnormality

Meaning #2: not characterized by a fixed principle or rate; at irregular intervals
  Synonym: unregularity
  Antonym: regularity (meaning #2)

Meaning #3: an irregular asymmetry in shape; an irregular spatial pattern
  Synonym: geometrical irregularity

Meaning #4: irregular and infrequent or difficult evacuation of the bowels; can be a symptom of intestinal obstruction or diverticulitis
  Synonym: constipation