In cricket, a batsman may retire from an innings at any time when the ball is dead; they must then be replaced by a teammate who has not been dismissed. The most common reason for retirement is if the batsman becomes injured or unwell, in which case the situation is officially recorded on the scorecard as "retired - not out"). If a batter retires without any injury or illness, he/she is considered retired out. A retired out batter is not allowed to resume the innings. According to ICC laws, a player is considered retired out if the player leaves the crease without the umpires permission.
In summary, "retired out" is a term used in cricket when a batter retires without any injury or illness, and is not allowed to resume the innings.
