The phrase "unstoppable shot" means a shot that cannot be prevented or blocked by the opposing team. It is a powerful and accurate shot that is almost certain to score a point. Full definition
LeBron James called it the second-most unstoppable shot in NBA history. (sbnation.com)
The Danish international fired home an almost unstoppable shot from the edge of the box past Argentine Willy Caballero in the Chelsea goal to make the scores 1 - 1 going into half time. (caughtoffside.com)
He launches an attack for Arsenal, he sees Welbeck making a run, he kicks the ball, the ball lands at Welbeck's feet, he notices Sanchez making a run, he passes the ball to Sanchez, Sanchez does his dribbling drills, two defenders are out, he had an option to either go for goal or pass the ball to an on - rushing Xhaka, he chose to lay the ball for Xhaka, who then fires an unstoppable shot into the net for our third goal!. (justarsenal.com)