means A soft knitted or woven covering for the foot, worn inside a shoe and reaching somewhere between the ankle and the knee.

from From Old English 'socc,' a light slipper, borrowed from Latin 'soccus' — a low-heeled shoe worn by comic actors on the Roman stage, as opposed to the high 'cothurnus' of tragedy. The Latin itself was likely picked up from Greek 'sykchos,' a kind of shoe, whose ultimate source is murky. So today's humble foot-tube traces back, improbably, to the footwear of ancient comedy — fitting for a garment with such a flair for disappearing acts.