tornado

Etymology

From earlier English ternado, attested since the 1550s as a nautical term for a windy thunderstorm. From Spanish tronada (“thunderstorm”), from tronar (“to thunder”), from Latin tonō (“to thunder”), from Proto-Indo-European *(s)tenh₂- (“to thunder”). The o and r were reversed in English (metathesis) under influence of Spanish tornar (“to twist, to turn”), from Latin tornō (“to turn”).

noun

1. (meteorology) A violent windstorm characterized by a mobile, twisting, funnel-shaped cloud.
   A tornado is a rotating column of air.
   An extreme version of vorticity is a vortex. The vortex is a spinning, cyclonic mass of fluid, which can be observed in the rotation of water going down a drain, as well as in smoke rings, tornados and hurricanes. 2013-03, Frank Fish, George Lauder, “Not Just Going with the Flow”, in American Scientist, volume 101, number 2, archived from the original on 2013-05-01, page 114