thinking cap

Etymology
Probably by analogy with, which is attested from the early 17th century.

Noun

 * 1)  A metaphorical piece of headgear supposedly worn by a person to assist them in thinking about how to solve a problem.

Translations

 * Chinese:
 * Mandarin:
 * Danish: tænkehat
 * Finnish: mietintämyssy
 * Italian:
 * Russian:
 * Serbo-Croatian: mislilačka kapa
 * Spanish: gorra de pensar
 * Swedish: tankehatt, tänkarhatt