A quick search (surprisingly) revealed no standards for describing the grind. Neither the "International Coffee Organization" nor the "National Coffee Association USA" offer much more than: (from NCAUSA)
If you purchase whole bean coffee, always grind your beans as close to
the brew time as possible. A burr or mill grinder is preferable
because all of the coffee is ground to a consistent size. A blade
grinder is less preferable because some coffee will be ground more
finely than the rest. If you normally grind your coffee at home with a
blade grinder, try having it ground at the store with a burr grinder.
You may be surprised at the difference!
An author at "About.com" does offer an rather functional definition, though it lacks the authority to be called a standard:
Coarse - Very distinct particles of coffee. Like heavy-grained kosher salt. Downright chunky.
Medium - Gritty, like coarse sand.
Fine - Smoother to the touch, a little finer than granular sugar or table salt.
Extra fine - Finer than sugar, but not quite powdered. Grains should still be discernable to the touch.
Turkish - Powdered, like flour. Most inexpensive (blade) grinders will be unable to grind this finely.