Tor*na"do (?), 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<-- twister -->.
© Webster 1913.