Wrong ball
Any ball other than the player's ball in play, including: another player's ball in play; a provisional ball or second ball played by another player; the player's own provisional ball or second ball that has been abandoned (see Rules 18.3c(2) and 18.3d(2)); the player's own original ball when it is no longer in play (for example, your first ball is out of bounds or has been treated as lost and you have put another ball into play under penalty); any stray ball.
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