1580s, “pertaining to cognition,” with -ive + Latin cognit-, past participle stem of cognoscere “to get to know, recognize,” from assimilated form of com “together” (see co-) + gnoscere “to know,” from PIE root *gno- “to know.”

Taken over by psychologists and sociologists after c. 1940. Cognitive dissonance “psychological distress cause by holding contradictory beliefs or values” (1957) apparently was coined by U.S. social psychologist Leon Festinger, who developed the concept. Related: Cognitively.