Longman Dictionary of Contemporary English - bolt

~1 n 1 »LOCK« a metal bar that you slide across a door or window to fasten it 2 »SCREW« a screw with a flat head and no point, for fastening two pieces of metal together 3 a bolt from out of the blue news that is sudden and unexpected  (It was a bolt out of the blue when Alan resigned - completely unexpected.) 4 bolt of lightning lightning that appears as a white line in the sky  (- see also thunderbolt) 5 make a bolt for (it) to suddenly try to escape from somewhere 6 »WEAPON« a short heavy arrow (1) that is fired from a crossbow (1) 7 »CLOTH« a large long roll of cloth  (- see also shoot your bolt shoot1 (20), the nuts and bolts of nut1 (6)) ~2 v 1 2 a) to suddenly start to run very fast because you are frightened  (The horse reared up and bolted.) b) to escape from somewhere  (Kevin had bolted through the open window.) 3 also bolt down to eat very quickly  (Don't bolt your food.) 4 to fasten two things together using a bolt1 (2)  (We had the safe bolted to the wall.) 5 to lock a door or window by sliding a bolt across ~3 adv sit/stand bolt upright to sit or stand with your back very straight