Definition of stand pat
If you are playing a poker variant like 2-7 Triple Draw or Razz, the stand pat is the moment when you tell everyone that you don't want to change your cards anymore. When you make a stand pat and, despite the possibility of changing cards, you don't do it, you are very strong. Your hand is even stronger if you make a stand pat on your first turn.
Origin of the expression stand pat
The origin of the expression is not certain, but it is believed to have originated in the early 1900s. The expression would have been used mainly in politics. To be "stand pat" had a pejorative connotation and meant that one was reactionary and closed to new ideas and change. Someone who is "stand pat" is someone who does not want to change, in this case, his ideas, in card poker! The expression was mostly used in the United States.