I've often noticed authors mistakenly using shutter and shudder, one in the place of the other. While these terms may be pronounced similarly, they are not interchangeable.
Shutter
A shutter is a panel--often wooden and decorative--usually fixed on the exterior of a window that may be closed for security or privacy. They are the wooden panels we usually see in various colors on the outside of the windows on houses. The verb shutter means to close shutters on a building.
Shudder
To shudder is to tremble or shake convulsively. This is a typical reaction to fear or another strong emotion, and it is often used in horror/ thriller works.