ro ‧ tor /ˈrəʊtə $ ˈroʊtər/ BrE AmE noun [countable] technical
[ Date: 1800-1900 ; Origin: rotator 'something that rotates' (17-21 centuries) , from Latin , from rotare ; ⇨ ↑ rotate ]
1 . a part of a machine that turns around on a central point
2 . ( also rotor blade ) the long flat part that turns around and around on top of a ↑ helicopter