From Longman Dictionary of Contemporary Englishwindmillwind‧mill /ˈwɪndˌmɪl/ noun [countable] 1 
TBTPa building or structure with parts that turn around in the wind, used for producing electrical power or crushing grain2 British EnglishDGO a toy consisting of a stick with curved pieces of plastic at the end that turn around when they are blown SYN pinwheel American English
TBTPa building or structure with parts that turn around in the wind, used for producing electrical power or crushing grain2 British EnglishDGO a toy consisting of a stick with curved pieces of plastic at the end that turn around when they are blown SYN pinwheel American EnglishExamples from the Corpus
windmill• There was only one low hill in sight, and this had an old, disused windmill on it.• However, Cauldron Barn Farm, inland on a ridge by the former windmill, survives.• The subsidies will cover up to 40 percent of installation costs of new windmills.• Today, modern versions of windmills, called wind turbines, are used to create electricity.• In fact, the windmill provided too much power.• For centuries, traditional windmills harnessed the wind to drive machinery for grinding wheat into flour.• In some areas he could plant his land with windmills. 