Trade winds - (n.)

Air flow from east to west and toward the equator (or the Intertropical Convergence Zone) roughly in the zone between the tropics of Cancer and Capricorn, although it can blow somewhat beyond those latitudes in some places. The trades got their name from English sailors, for their steadiness (as in the phrase, "the wind blows trade," i.e. on track). See also “General Circulation of the Atmosphere.”