There are several synonyms for the word "windsail." One of the most common is "ventilator," which can refer to an object used to circulate air in a space. Another synonym for "windsail" is "sailpipe," which is often used to describe a tube-shaped object that is used to direct air or ventilation. Lastly, "ventilation tube" can also be used as a synonym for "windsail," especially when describing a device that is used to regulate air flow in a specific space. Regardless of the specific synonyms used, all of these terms refer to a device or object that is used to regulate the flow of air or ventilation in a space or environment.