köken: Uncertain. Perhaps a Lombardic or Carolingian era borrowing from Old High German barrezzen (“to hate”) or maybe from French page (“page, serving boy”), probably via Neapolitan pazzo (compare French adage “être effronté comme un page”). Alternatively from Latin patiēns (“suffering”). Compare Sicilian pacciu.
köken: From Middle Dutch geck (“madman”). Earlier origin uncertain, but perhaps from an imitative verb also found in Swedish gäcka (“to mock”). Cognate with German Geck, Jeck, English geek (see etymology there).
aile: gek als een deur, gek als een ui, gekke Henkie, gekkerd, gekkig, gekmakend, gekscheren, knettergek, stapelgek
köken: From Byzantine Greek τρελός (trelós), from Koine Greek τρηρός (trērós), from Ancient Greek τρήρων (trḗrōn). The chess sense is a semantic loan from French fou.