tor·na·do 
(tôr-nādō)
(tôr-nādō)n. pl. tor·na·does or tor·na·dos
1. A violently rotating column of air extending from a cumulonimbus cloud to the ground, ranging in width from a few meters to more than a kilometer, with destructive winds up to 510 kilometers (316 miles) per hour or higher. Tornadoes are typically associated with a funnel cloud pendant from a storm's wall cloud, often extending to the bottom of the tornado.
2. A violent thunderstorm in western Africa or nearby Atlantic waters.
3. A whirlwind or hurricane.
[Alteration (probably influenced by Spanish tornado, turned, past participle of tornar, to turn) of Early Modern English ternado, violent thunderstorm, hurricane from Spanish tronada, thunderstorm, from tronar, to thunder, from Latin tonāre; see (s)tenə- in the Appendix of Indo-European roots.]
tor·nadic (-nādĭk, -nădĭk) adj.
tornado