abroad: [13] It was only in the 15th century that abroad came to mean ‘in foreign parts’. Earlier, it had been used for ‘out of doors’, a sense still current today, if with a rather archaic air; but originally it meant ‘widely’ or ‘about’ (as in ‘noise something abroad’). It was formed quite simply from a ‘on’ and the adjective broad, although it was probably modelled on the much earlier (Old English) phrase on brede, in which brede was a noun, meaning ‘breadth’. => broad[abroad etymology, abroad origin, 英语词源]