what are the arms on a windmill called
The smock mill Goliath in front of the wind farm Growind in Eemshaven in the Netherlands. A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades. Centuries ago, windmills usually were used to mill grain, pump water, or both. Thus they often were gristmills, windpumps, or both.