windmill

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A machine that runs on the energy generated by a wheel of adjustable blades or slats rotated by the wind.
2. n. Something, such as a toy pinwheel, that is similar to a windmill in appearance or operation.
3. v. To move or cause to move like the wheel of a windmill; rotate sweepingly.
4. idiom. tilt at windmills To confront and engage in conflict with an imagined opponent or threat.

Century Dictionary and Cyclopedia

1. n. A mill or machine for grinding, pumping, or other purposes, moved by the wind; a wind-motor; any form of motor for utilizing the pressure of the wind as a motive power. Two types of machines are used, the horizontal and the vertical. The vertical motor consists essentially of a horizontal shaft called the wind-shaft, with a combination of sails or vanes fixed at the end of the shaft, and suitable gearing for conveying the motion of the wind-shaft to the pump or other machinery. The older types of windmill used four vanes or sail-frames called whips, covered with canvas, arrangements being provided for reefing the sails in high winds. To present the vanes to the wind, the whole structure or tower carrying the windmill was at first turned round by means of a long lever. Later the top of the tower, called the cap, was made movable. Windmills are now made with many wooden vanes forming a disk exposed to the winds, and fitted with automatic feathering and steering machinery, governors for regulating the speed, apparatus for closing the vanes in storms, etc. These improved windmills are chiefly of American invention, and are largely used in all parts of the United States for pumping water. Horizontal windmills employ an upright wind-shaft, and movable vanes placed in a circle round it, the vanes feathering when moving against the wind.
2. n. A visionary scheme; a vain project; a fancy; a chimera.

Wiktionary

1. n. A machine which translates linear motion of wind to rotational motion by means of adjustable vanes called sails.
2. n. The structure containing such machinery.
3. n. A child's toy consisting of vanes mounted on a stick that rotate when blown by a person or by the wind.
4. n. basketball A dunk where the dunker swings his arm in a circular motion before throwing the ball through the hoop.
5. n. A guitar move where the strumming hand mimics a turning windmill.
6. n. juggling The false shower.
7. v. transitive, intransitive To rotate (itself) with a sweeping motion.
8. v. intransitive Of a rotating part of a machine, to (become disengaged and) rotate freely.

GNU Webster's 1913

1. n. A mill operated by the power of the wind, usually by the action of the wind upon oblique vanes or sails which radiate from a horizontal shaft.

WordNet 3.0

1. n. generator that extracts usable energy from winds
2. n. a mill that is powered by the wind