dub [OE] It has been possible to dub someone a knight since the Norman Conquest, at a time when Old English was still hanging on: the king conferred the rank by ceremonially touching the person being honoured on the shoulder with a sword. It came from a shortened form of Old French adober meaning ‘to equip with armour’ or ‘to repair’. The sense of giving an unofficial title, name, or nickname to someone [E17th] developed from this ritual conferring of a knighthood.

Since the 1920s to dub a film has been to provide it with an alternative soundtrack, now usually in another language. Dub [1970] is also a kind of music in which some vocals and instruments are removed and the bass guitar accentuated. In these uses dub is a shortening of double (see two).