The name derives from the fact that it surrounds and hides the main building like the cuff (裳裾, mosuso) of a pair of pants.
[3] Its purpose was in fact to hide the thick sustaining pillars of the structure, making it look lighter and simpler.
[2] This name started being used during the Middle Ages, and stems from the idea that its presence offered protection from snow.
The first of the kon-dō's (main hall, National Treasure, see gallery) two stories at Hōryū-ji has a mokoshi, which was added in the Nara period with extra posts.
[3] The butsuden (main hall) of a Zen temple usually has a mokoshi, and therefore looks like a two-story building (see photo above and gallery), although in fact it is not.