Fan has two common meanings:

1. A device that moves air to cool you down. An electric fan has blades that spin rapidly, pushing air across a room on a hot day. Before electricity, people used handheld fans made of paper, fabric, or feathers, waving them back and forth to create a breeze. Some fans fold up and fit in your pocket, while ceiling fans stay mounted overhead. The word can also be a verb: when you fan yourself with a magazine, you're moving it to create cooling air.
2. Someone who enthusiastically admires and supports a person, team, sport, or interest. A basketball fan follows their favorite team's games and cheers from the stands or couch. Music fans collect albums and attend concerts. The word suggests genuine excitement and loyalty that shows in how fans spend their time and money. You might be a fan of a book series, spending your allowance on the next volume the day it comes out, or a fan of gymnastics, practicing moves and watching competitions whenever you can.

True fans stick with their teams even during losing seasons and support their favorite authors when friends criticize them.