When a stock’s price becomes several times its purchase price, it is known as multi bagger.
e.g. if one buys a stock for 100, when its price becomes 200 it is 2-bagger, when the price becomes 300 it is 3-bagger. As the price goes to 400, 500, 600 it becomes a multi-bagger since it’s returns are several times.
e.g Ceatltd was around 100 back in Aug of 2013. Currently it is trading at around 600.