* The children built a fort out of blankets and pillows in the living room.
* The old fort stood on a hill overlooking the valley, a silent reminder of past battles.
* The soldiers stationed at the fort were vigilant against enemy attack.
* She felt safe and secure inside the fort of her own home.
* The pioneers built a fort to protect themselves from Native American attacks.
These are just a few examples, and the context will dictate how you use the word "fort".