irrational

(noun) a real number that cannot be expressed as a rational number. Synonyms: irrational number.

(adj) not consistent with or using reason. Synonyms: irrational (vs. rational). Examples: "Irrational fears." "Irrational animals."

(adj) real but not expressible as the quotient of two integers. Synonyms: irrational (vs. rational). Example: "Irrational numbers."