Tornado (?), n.; pl. Tornadoes (#). [From Sp. or Pg. tornar to turn, return, L. tornare to turn, hence, a whirling wind. The Sp. & Pg. tornada is a return. See Turn.] A violent whirling wind; specifically (Meteorol.), a tempest distinguished by a rapid whirling and slow progressive motion, usually accompaned with severe thunder, lightning, and torrents of rain, and commonly of short duration and small breadth; a small cyclone.
[1913 Webster]