Scared money is a casino term used to refer to the money a player cannot afford to lose, or simply to refer to their playstyle.
For example, before players sit at a casino table, they decide on their bankroll and calculate how much they can afford to lose. However, in some cases, especially in a game of poker, players might get more chips than they plan to spend in order to get more leverage and potentially win bigger hands by playing with higher stakes. In other words, they are not planning on spending that money.
A lot of good poker players often try to predict other players’ hands and play based on the information other players give them, such as how often and when they bet, thus understanding why someone is betting. However, if a player is playing with scared money, they might make rash or unpredictable decisions, which is where the term comes in handy to refer to someone being nervous at the table.