Fore! "Fore" is another word for "ahead" (think of a ship's fore and aft). Yelling "fore" is simply a shorter way to yell "watch out ahead" (or "watch out before").
You’re reading this article because you play golf and have spent various periods of time working on a shot or a part of the swing that you want to improve.
Fore!
The etymology for the word "Fore!" is not absolutely agreed. The Oxford English Dictionary records its first use in 1878 as a warning cry to people in front of a golf stroke and, like most people, believes it is an abbreviation of the word 'before'.