what's 1/2 and ounce in drops?

That would depend on whether the ounces were British fluid or U.S. fluid. My source says 360 drops for 1.0 U.S. fluid ounce, so ½ of one of these ounces would be 180 drops.

Looks like a good time to research the definition of 'drop'.....

That would depend on the density of the fluid. Perhaps you mean ½ a Fluid Ounce?

The "official" number of drops in 1 Fl Oz is about 986, so ½ Fl Oz would have just under 500 drops.