Definition of ss
ss means "shortstack". We can be shortstack for 2 main reasons. When you are shortstack in tournament, it is because the blinds have increased a lot and you have not won enough pots to preserve yourself at 100bb (100bb is what is called a classic stack, it is a reference). When we are shortstack in tournament (let's say between 2 and 30 big blinds), it is not by will, but by force of circumstance. When you are shortstack in cash games, it's because you prefer a game with fewer chips. Often shortstack will have push bb and will only play 2 streets most of the time, preflop and flop. They are called the shortstacks pros.
The shortstack pros
An shortstack pro is a player who plays games of cash games with a systematic push bb. When he doubles his stack, he leaves the table to join a new one with his push bb. This strategy avoids having to play multiple streetss. It is a simpler poker game. Most of the time, the player shortstack push or fold. These players take advantage of the time when several players are not adjusting well against the shortstacks.