For a player who receives a pass or gains possession of a loose ball, the gather is defined as the point where the player gains enough control of the ball to hold it, change hands, pass, shoot, or cradle it against his body.
For a player who is in control of the ball while dribbling, the gather is defined as the point where a player does any one of the following:
Puts two hands on the ball, or otherwise permits the ball to come to rest, while he is in control of it;
Puts a hand under the ball and brings it to a pause; or
Otherwise gains enough control of the ball to hold it, change hands, pass, shoot, or cradle it against his body.
Regardless, it's a stupid rule. If you can poll 10 knowledgeable fans and more than half of them can't explain a rule, it's a dumb rule.