Their name originally derives from the late Middle English word 'trade' (borrowed from Middle Low German, and cognate with English 'tread'), meaning "path" or "track," and thence the obsolete nautical phrase "the wind blows trade," that is to say, on a consistent track. However, by the 18th century, because of the importance of these winds to England's merchant fleet crossing the Atlantic Ocean, both etymologists and the general public had come to identify them with a later meaning of 'trade', "(foreign) commerce". For relation to European shipping and exploration see Winds in the Age of Sail.