na-adjective, noun which may take the genitive case particle 'no', noun
irreducible
Mathematics term for something that cannot be simplified further, such as a fraction or polynomial.
This fraction is in its simplest form.
Factor into irreducible polynomials.
irreducible representation
one particle irreducible
Compound of 既 (already) and 約 (abbreviation, reduction), literally 'already reduced'. The exact historical derivation is uncertain; the spelling is conventionally associated with the mathematical meaning.