burn [OE] The burn meaning ‘to be on fire’ and the Scottish word for a small stream are not connected, although both are Old English from common Germanic roots. To burn the midnight oil [M17th], ‘to read or work late into the night’, and to burn the candle at both ends [M18th], ‘to go to bed late and get up early’, both recall the days before gas and electricity, when houses were lit by candles and oil lamps. To burn your boats [L19th] (in Britain also to burn your bridges) [M18th] derives from military campaigns. Burning the boats or bridges that a force used to reach a particular position would mean that they had destroyed any means of escape or retreat: they had no choice but to fight on.