windmill

UK: /ˈwɪndmɪl/ US: /ˈwɪndˌmɪl/ ,(wind′mil′)

WordReference Random House Learner's Dictionary of American English © 2025

wind•mill /ˈwɪndˌmɪl/   n. [countable]

1. Energy, Mechanical Engineering a machine for grinding or pumping, usually a building with a structure of four sails on the outside that is spun and driven by the wind acting on the sails.

v. 

2. to (cause to) move like a windmill: [no object]
   His arms were windmilling.
   [~ + object]
   windmilling his arms.

WordReference Random House Unabridged Dictionary of American English © 2025

wind•mill  (wind′mil′), n. 

1. Energy, Mechanical Engineering any of various machines for grinding, pumping, etc., driven by the force of the wind acting upon a number of vanes or sails.
2. Energy (loosely) a wind generator;
   wind plant.
3. Aeronautics a small air turbine with blades, like those of an airplane propeller, exposed on a moving aircraft and driven by the air, used to operate gasoline pumps, radio apparatus, etc.
4. an imaginary opponent, wrong, etc. (in allusion to Cervantes' Don Quixote):
   to tilt at windmills.

v.i., v.t. 

5. Aeronautics (of a propeller engine or turbojet engine) to rotate or cause to rotate solely under the force of a passing airstream.

• 1250–1300; Middle English; see wind¹, mill¹

Collins Concise English Dictionary © HarperCollins Publishers::

windmill / ˈwɪndˌmɪl ˈwɪnˌmɪl/ noun

1. a machine for grinding or pumping driven by a set of adjustable vanes or sails that are caused to turn by the force of the wind
2. the set of vanes or sails that drives such a mill
3. Also called: whirligig a toy consisting of plastic or paper vanes attached to a stick in such a manner that they revolve like the sails of a windmill
4. an imaginary opponent or evil (esp in the phrase tilt atorfight windmills)
5. an informal name for helicopter
6. an informal name for propeller1

verb

1. to move or cause to move like the arms of a windmill