subrational
/ˌsʌbˈraʃ(ə)n(ə)l/ /ˌsʌbˈraʃən(ə)l/adjective
1Less than rational; without the faculty of reasoning.
2Existing or occurring below the level of the rational.
Origin
Mid 19th century; earliest use found in The Daily Telegraph. From sub- + rational.