A coworker is someone who works at the same place you do, doing their own job while you do yours. The word combines “co,” meaning together or with, and “worker,” so coworkers are people who share a workplace.

Your teacher's coworkers are the other teachers at your school. A firefighter's coworkers are the other firefighters at the station. In an office, coworkers might sit at nearby desks, attend the same meetings, and collaborate on projects. At a restaurant, coworkers might be the servers, cooks, and dishwashers who all help keep things running smoothly.

Coworkers aren't necessarily friends, though they can be. They're simply people connected by working for the same organization. Some coworkers become close friends outside of work, while others maintain a friendly but professional relationship.

Coworker usually describes a peer relationship. Your teacher is not your coworker because you're a student, not an employee of the school. Similarly, a boss and an employee might work together closely, but they're not usually called coworkers because one supervises the other.