The Collaborative International Dictionary
Smock \Smock\, a. Of or pertaining to a smock; resembling a smock; hence, of or pertaining to a woman.
Smock mill, a windmill of which only the cap turns round to meet the wind, in distinction from a post mill, whose whole building turns on a post.
Smock race, a race run by women for the prize of a smock.
Wiktionary
n. A windmill of which only the cap turns round to meet the wind, in distinction from a post mill, whose whole building turns on a post.
Wikipedia
The smock mill is a type of windmill that consists of a sloping, horizontally weatherboarded or thatched tower, usually with six or eight sides. It is topped with a roof or cap that rotates to bring the sails into the wind. This type of windmill got its name from its resemblance to smocks worn by farmers in an earlier period.