Nominal Yield
  
The coupon, or percentage that the bond makes, is the nominal yield of a bond—and it always stays the same. The bond may trade up or down, but the nominal yield stays the same.
By the way, "nom" means "name" in Latin. We showed up in class that day.
Example:
A bond has a $1,000 par value, 8% coupon, and is due 2034. In trade, the bond might be worth $800 a year from now, $1,200 six months from now, and so on. The nominal yield, though, is 8%. Is now, and always will be.