ESPN's scorecard graphic for the Open Championship is labeled "front nine" and "back nine," but the Old Course doesn't have a front and back. You play nine holes "out," making a little loop at the bend of the shepherd's crook, then nine holes "in." "Outward nine" and "inward nine" -- the preferred local terms -- would be more accurate.
And there many variants.
"Front" and "back" actually don't make sense on many golf courses. It's rare to find a club at which the first nine holes you play are laid out in front of something, and the second nine holes are laid out in back of the same thing. Sometimes the nines are right and left; sometimes the holes are all over the place; sometimes -- as on nine-hole courses, where you play the same holes twice -- the nines are essentially on top of each other (upper and lower?).
Bobby Jones wanted TV announcers to refer to the nines at Augusta National as the "first nine" and the "second nine," partly because "front" and "back" weren't accurate, and partly because he felt that "back side" -- a popular variant -- was indecently anatomical. One nice thing about "first nine" and "second nine" is that they work for any golf course, including your course, my course, and the Old Course. Golfers will never change, naturally -- but if it came to a vote I'd go with Jones.