Options Trading Tutorial - what's the definition of restricted stock?

what's the definition of restricted stock?

I know about preferred, common and stock options, but companies are now rewarding their directors with "restricted" stock. What's that?

Stock that can't be sold for some specified period of time.
In laymans terms, it's stock that is not registered for sale to the public. The stock can be registered for sale after the restriction is met. The restriction is usually a specific length of holding time and/or paperwork (Rule 144) that has to be filed with the SEC. If you want the real technicals on restricted stock than you can read this http://www.sec.gov/divisions/corpfin/33act/index1933.shtml It also cures insomnia!!
Restricted stock is as Steve says and the reason you are hearing more about it now is because of the stock options scandals. Additionally some employees (non executives usually) don't like the abstract value of stock options and prefer to have an easier to understand product.