"give a name to," originally "make a knight," from late Old English dubbian "knight by ceremonially striking with a sword" (11c.), a word perhaps borrowed from Old French aduber "equip with arms, adorn" (11c.) which is of uncertain origin, probably Germanic, but there are phonetic difficulties. Meaning "provided with a name" is from 1590s. Related: Dubbed; dubbing.
"add or alter sound on film," 1929, shortening of double (v.); so called because it involves making an additional recording of voices and combining it with the soundtrack. The type of re-mixed reggae music was so called from 1974, probably for the same reason. Related: Dubbed; dubbing.