Anemometer 

A device which is used to measure wind speed. 

Chatter 

Chatter is a condition that occurs on a two-bladed machine as it turns with the wind.  Picture, if you will, a two bladed machine as it spins.  When the blades are horizontal and rotating, it is dynamically difficult for the machine to follow changes in wind direction.  When the blades are vertical, it is easy for the machine to yaw with the wind.  Now, if we speed that action up to several hundred rpm or more,  the machine incrementally moves to follow the wind with each revolution of the blades.  It is kind of like a ratcheting action which can resonate in the tower and can be audible. 

Chinese finger 

Also known as a Kellem grip.  This is a device used to provide strain relief for wires.  A typical wind turbine's electrical connections cannot sustain the forces associated with the gravitational pull on the wires.  This device holds the wires.  It can be found under "wire grip" in the Grainger catalog.  (Thanks to Ken Starcher for this information.) 

Flutter 

This is a form of governing.  When blades flutter, they are make very loud noises.  Some have likened it to a huey helicopter in your backyard, and others have said it's like having your own Formula One race car in your backyard.   

Furling 

See governing. 

Governing 

The energy in the wind is proportional to velocity (wind speed) cubed.  If you double the wind speed, you get 8 times the energy.  Turbines need to shed some of that energy or they will self-destruct.  Governing is the term used to describe what the turbine does to protect itself during high (> 30 mph) winds. 

Grid Intertie 

This is the term used to describe a normal utility connection that would be used to sell excess power back to the local utility. 

HAWT 

Horizontal Axis Wind Turbine. The axis of the wind turbine is horizontal, as opposed to vertical (VAWT). 

kWh 

This is a unit of energy.  There are common misconceptions about the use of this terminology.  Please see http://groups.yahoo.com/group/awea-wind-home/message/253 for a good explanation of energy and power units of measure. 

rpm 

Revolutions per minute. 

Turbulence 

This describes, generally speaking, how smooth the air flow is through the turbine.  Turbulent sites have winds that are constantly changing speed and/or direction. 

VAWT 

Vertical Axis Wind Turbine.  The axis of the wind turbine is vertical, the blades stand straight up.  These are commonly known as egg-beaters. 

Wind Turbine 

A device which converts kinetic energy from moving air to another energy form.  Typically, kinetic energy is converted to rotational energy to pump water or to generate electricity. 

Yaw 

A wind turbine "yaws" as it follows the wind.  This action of following the wind is called yaw.  Upwind turbines have a tail so that the blades can stay in the wind.  Downwind turbines don't need a tail.