The adjective rigged is used when mathematically improbable events continue to occur in (favor of) a player. This may include so-called setups in which a player hits several strong hands in a row, but is always inferior to an even stronger hand, and on the other hand an accumulation of suckouts, ie the loss of a hand, after the chips as (high) Put the favorite in the middle and still be stretched by the few outs of the opponents.
There is also the convention of calling online poker room rigged if you make losses over a longer period of time, even though you are acting mathematically correct. The subjective sensation of being stretched much more often than others leads players to blame the poker room. Assumptions that poker rooms are rigged, ie determine hand histories to the detriment of a player or a group of players, have not yet been empirically proven.