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Old English þoht, geþoht, from stem of þencan "to conceive of in the mind, consider" (see think). Cognate with the second element in German Gedächtnis "memory," Andacht "attention, devotion," Bedacht "consideration, deliberation." Second thought "later consideration" is recorded from 1640s. Thought-crime is from "Nineteen Eighty-Four" (1949); thought police is attested from 1946, originally in reference to pre-war Japanese Special Higher Police (Tokubetsu Koto Keisatsu).
The act or the process of thinking; cogitation.
A product of thinking, such as an idea.
The faculty of thinking or reasoning.