Definition: Definitions from the Official Rules of Golf appear courtesy of the USGA.
Lost Ball: A ball is deemed "lost" if:
- a. It is not found or identified as his by the player within
five minutes after the player’s side or his or their caddies
have begun to search for it; or
- b. The player has made a stroke at a provisional ball from the
place where the original ball is likely to be or from a
point nearer the hole than that place (see Rule 27-2b); or
- c. The player has put another ball into play under penalty of
stroke and distance (see Rule 27-1a); or
- d. The player has put another ball into play because it is
known or virtually certain that the ball, which has not
been found, has been moved by an outside agency (see Rule
18-1), is in an obstruction (see Rule 24-3), is in an abnormal
ground condition (see Rule 25-1c) or is in a water hazard (see
Rule 26-1); or
- e. The player has made a stroke at a substituted ball.
Time spent in playing a wrong ball is not counted in the five-minute period allowed for search.
