irregular

The definition of irregular is something that doesn't conform to accepted or normal standards or that doesn't occur at regular intervals.

(adjective)

When you go to the doctor on no set schedule, this is an example of a situation where you make irregular visits to the doctor.
When you do not behave like your usual self, this is an example of a situation where your behavior is irregular.

See irregular in Webster's New World College Dictionary

adjective

not conforming to established rule, method, usage, standard, etc.; out of the ordinary; anomalous
not conforming to legal or moral requirements; lawless; disorderly
not straight or even; not symmetrical; not uniform in shape, design, or proportion
uneven in occurrence or succession; variable or erratic
☆ having minor flaws or imperfections: said of merchandise
experiencing constipation
Bot. not uniform in shape, size, etc. as the petals of a flower
Gram. not inflected in the usual way: “go” is an irregular verb
Mil. not belonging to the regularly established army

Origin: ME < OFr irregulier < ML irregularis: see in- & regular

noun

Related Forms:

See irregular in American Heritage Dictionary 4

adjective

Contrary to rule, accepted order, or general practice: irregular hiring practices.
Not conforming to legality, moral law, or social convention: an irregular marriage.
Not straight, uniform, or symmetrical: irregular facial features.
Of uneven rate, occurrence, or duration: an irregular heartbeat.
Deviating from a type; atypical.
Botany Having differing floral parts, as of a zygomorphic or asymmetrical flower.
Falling below the manufacturer's standard or usual specifications; imperfect.
Grammar Departing from the usual pattern of inflection, derivation, or word formation, as the present forms of the verb be or the plural noun children.
Not belonging to a permanent, organized military force: irregular troops.