[adjective] - not using reason or clear thinkingIt's totally irrational, but I'm frightened of mice.The irrational consumer is one who fails to respond to a cheap price even when goods are identical in all other respects.His parents were worried by his increasingly irrational behaviour.
IRRATIONAL
Meaning of IRRATIONAL in English
Cambridge English vocab. Кембриджский английский словарь. 2012