To hole up means to hide or shelter yourself somewhere, usually for safety or to avoid something unpleasant. When a snowstorm hits, your family might hole up at home with blankets, hot chocolate, and board games, staying inside until the weather clears. When someone is sick, they might hole up in their bedroom to rest and recover.

The phrase comes from the way animals like bears and rabbits retreat into holes or dens for protection. A rabbit being chased by a fox will hole up in its burrow. In stories about the Old West, outlaws would hole up in remote cabins to hide from the law.

You can use this phrase when you're deliberately staying somewhere to focus or get something done. A writer might hole up in a quiet cabin to finish a book without distractions. Students sometimes hole up in the library during exam week, creating a temporary study hideout.

The phrase means deliberately taking shelter or hiding away, with the sense that you’re not coming out until conditions improve or until you’ve finished what you’re doing.