colour [ME] In Old French it was spelled colour, in Latin color. The main English spelling has been colour since the medieval period, though color, now the usual spelling in American English, was sometimes used from the 15th century onwards. Since the late 16th century the distinguishing flag of a ship or regiment has been known as its colours, a meaning that lies behind a number of common English expressions. To show your true colours [M16th] is to reveal your real character or intentions, especially when these are disreputable. A ship engaged in illegal trading or in time of war might fly a bogus flag to deceive the authorities or the enemy, a practice known as ‘sailing under false colours’ [LME]. If the ship subsequently revealed itself to the enemy by firing on them or fleeing, it was ‘showing its true colours’. The phrase nail your colours to the mast [E19th], meaning ‘to declare openly and firmly what you believe or support’, is also naval: a ship in battle might nail a damaged flag to the mast so that there was no possibility of it being seen as lowered in defeat. And to come through with flying colours [L17th] is to come successfully through a test, like a victorious warship returning to port with its flag unscathed.