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1560s, "a circular motion;" as a verb, "to turn round," early 15c.; from Latin gyrus "circle, circular course, round, ring," and its derived verb gyrare, from Greek gyros "circle, ring," related to gyrós "rounded," perhaps from PIE root *geu- "to bend, curve" (cf. Armenian kor "crooked," Lithuanian gurnas "hip, ankle, bone," Norwegian kaure "a curly lock of hair").
A spiral oceanic surface current driven primarily by the global wind system and constrained by the continents surrounding the three ocean basins (Atlantic, Pacific, and Indian). Each ocean basin has a large gyre in the subtropical region, centered around 30° north and south latitude. Smaller gyres occur at 50° north latitude in the North Atlantic and Pacific Oceans. The direction of a gyre's rotation is determined by the prevailing winds in the region, with the large subtropical gyres rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.