Many times you will find watches being described as "overwound".  But what does that really mean?  Well, what it has become to mean that the watch is wound up all the way, but will not run. 

Technically, you cannot overwind most wrist and pocket watches, modern or antique.  They are supposed to be wound up all the way, until you cannot wind it up further with your fingertips.  Most watches, when properly serviced, will run for 28 to 30 hours or more on a full wind.

The bottom line...  when a watch is described as "overwound", it means that it has a problem causing it not to run.  It could be routine maintenence, such as cleaning and oiling, or it could be more serious, like a broken jewel, pivot, balance staff, etc.

-Courtesy PocketWatchSite.com