either of two belts over the oceans at c. 30° - 35° north and south latitude, characterized by calms, light wind, high barometric pressure, and hot, dry weather
See horse latitudes in American Heritage Dictionary 4
plural noun
Either of two belts of latitudes located over the oceans at about 30° to 35° north and south, having high barometric pressure, calms, and light, changeable winds.