Origin: Latin suffix -ular
Irregular has 13 different meanings across 2 categories:
A soldier who is not a member of an official military force and who may not use regular army tactics.
"The irregulars, lacking proper training in conventional warfare, relied on guerrilla tactics to ambush the occupying forces."
In plain English: An irregular is someone who does not follow normal rules or patterns, often acting unpredictably compared to others.
"The doctor ordered tests to check for any irregular growths in his lung tissue."
(used of the military) not belonging to or engaged in by regular army forces
"irregular troops"
"irregular warfare"
(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
"The scientist used water displacement to find the volume of the irregular rock since its jagged shape made direct measurement impossible."
failing to meet a standard of manufacture due to an imperfection
"an irregular pair of jeans"
(of a surface or shape); not level or flat or symmetrical
"walking was difficult on the irregular cobblestoned surface"
independent in behavior or thought
"she led a somewhat irregular private life"
"maverick politicians"
nonstandard; not conforming to rules or expectations
"The student's irregular handwriting made it difficult for the teacher to read her notes."
In plain English: Irregular means something that does not follow normal rules, patterns, or shapes.
"The baby's teeth came in irregularly, with some appearing before others."
Usage: Use irregular as an adjective to describe anything that does not follow standard patterns, such as verbs with unpredictable past tenses. Do not confuse this term with the noun form referring specifically to untrained soldiers outside official military forces.
The word irregular comes from the Medieval Latin irrēgulāris, which combined the prefix in- meaning "not" with regularis meaning "regular." This term was adopted into English through Middle English and Old French.