Ganaches, also spelled garnaches, and gardcorps were over coats worn by men of all social classes during the Middle Ages (c. 500–c. 1500). Most likely made of thicker wool, the primary purpose of these garments was to protect the wearer from inclement weather and provide warmth. They might even be lined with fur for extra warmth. They were worn from about 1200 on.
Ganaches and gardcorps were very similar. Both garments were pulled over the head and hung down past the waist, perhaps as far as the knees. The sleeves of the ganache were formed from extended fabric at the shoulders; they were open at the underarm and the sleeves were generally no longer than the elbow. The gardcorps had separately attached sleeves and thus was better for cold weather. Both garments could have a hood that attached at the back of the neck that was draped over the back when not in use.
Payne, Blanche, Geitel Winakor, and Jane Farrell-Beck. The History of Costume. 2nd ed. New York: HarperCollins, 1992.