Irrasjonell

Irrrasjonell is a Norwegian adjective meaning not rational or not based on reason. It describes beliefs, decisions, or actions that lack a solid logical or evidential basis, often implying impulsiveness, emotion, or bias. In everyday use it can carry a critical tone, but it is also employed in philosophical, psychological, or analytical contexts to distinguish what is reasoned from what is not. The related noun is irrasjonalitet and the adverb is irrasjonelt.

Etymology and related forms: The word is built from the stem rasjonell (rational) with the negating prefix ir-, and it is cognate with similar terms in other European languages, such as irrational (English) and irrationnel (French). The root ultimately derives from Latin ratio, meaning reason or calculation.

Mathematical meaning: In mathematics, an irrational number is a real number that cannot be expressed as a ratio of two integers. Its decimal expansion is non-terminating and non-repeating. Classic examples include pi (π) and the square root of 2. The concept is language-independent, but it is routinely discussed in Norwegian mathematical literature as part of real analysis and number theory. Irrational numbers contrast with rational numbers, which can be expressed as a ratio of integers and have terminating or repeating decimals.