Tarmac

I've been helping someone with English and American culture (shameless plug), and we read an article about a plane accident, which had the word "tarmac". If you think about it, it's sort of a weird word to use for a place where airplanes sit before they get on the runway to take off. What's puzzling is the source of it, and that it's a trademark. Usually I don't think of words coming from trademarks, but according to The Word Detective , it's:

short for "tar macadam." John McAdam (1756-1836) invented the "macadam" type of road pavement made of crushed stone, which resisted the rutting formerly plaguing highways in England. "Macadamizing" was later further improved by the addition of tar as a binder, resulting in the "Tarmac" process still widely used today.

Who would've known a commercial application would become a common, though odd-sounding, word.