trade: [14] Trade originally meant ‘way, track’. Not until the 16th century did the modern sense ‘buying and selling’ emerge, via ‘regular path followed by someone’ and ‘business pursued by someone’. Etymologically, it amounts to a ‘trodden’ path; for it was borrowed from Middle Low German trade ‘track’, which goes back ultimately to the prehistoric Germanic base *trad-, *tred-, source also of English tread and trot. => tread, trot[trade etymology, trade origin, 英语词源]