lock [OE] They seem like very different words, but the lock that is a fastening mechanism and the lock of hair may be related. Both are Old English, and possibly derive from a root that meant ‘to bend’. The lock [ME] in a river developed from the sense ‘an enclosure’ [OE] that was part of the original sense of the fastening mechanism called lock. All the elements in lock, stock, and barrel are parts of an old-fashioned firearm, although only the stock and barrel are found in modern guns. The lock was the mechanism for exploding the charge, the stock is the part to which the firing mechanism and barrel are attached, and the barrel is the cylindrical tube out of which the shot or bullet is fired. The expression first appears in the early 19th century in the alternative version stock, lock, and barrel, used by the novelist Sir Walter Scott.