Origins
The word 'trade' underwent one of the English language's most dramatic semantic transformations, evolving from a word meaning 'footpath' into one of the foundational terms of capitalism. Its etymology reveals that commerce, in the English-speaking imagination, began as a metaphor for walking a well-trodden path.
The word entered Middle English in the fourteenth century from Middle Low German 'trade' (track, course, path), from Proto-Germanic *tradō (track, trail), ultimately from PIE *dreh₂- (to tread, to step, to walk). The same PIE root produced the native English verb 'tread' and its past tense 'trod.' In its earliest English uses, 'trade' meant simply 'a path' or 'a track' — a physical route across the ground.
The semantic evolution proceeded through a series of logical extensions. 'A path' became 'a habitual course' (the path one regularly walks), which became 'a way of life' or 'a customary practice,' which became 'a regular occupation' (the course of activity one follows), which became 'a skilled craft' (a tradesman's occupation), and finally 'the act of buying and selling' (the commercial activity that defines a merchant's occupation). Each step is a small metaphorical extension of the previous one, but the cumulative distance from 'footpath' to 'international commerce' is vast.
Development
The dual modern meaning of 'trade' — both 'commerce' and 'a skilled manual occupation' (as in 'the building trades,' 'he learned a trade') — preserves two different stages of this evolution. The occupational sense crystallized in the sixteenth century, when guilds and apprenticeships structured economic life around specific crafts. The commercial sense emerged slightly later and eventually became dominant.
The phrase 'trade winds' preserves the oldest English sense of the word. The trade winds are steady, predictable winds that blow in a consistent path across the tropical oceans. They were called 'trade' winds not because they aided commercial shipping (though they did) but because they blew in a 'trade' — a regular, reliable track. The nautical term preserves the word's original meaning of 'a course' or 'a habitual path.' Sixteenth-century English speakers understood this perfectly; only later did the coincidence of 'trade' meaning both 'a path' and 'commerce' lead people to assume the winds were named for their economic utility.
The related compound 'trademark' (a distinctive mark identifying a trader's goods) dates from the sixteenth century. 'Tradesman' (a skilled craftsman or shopkeeper) dates from the same period. 'Trading post' (a commercial outpost) reflects the colonial expansion that made 'trade' one of the most consequential words in modern history, naming the activity that connected — and exploited — civilizations across the globe.