1. a person who exercises control or authority; a manager or supervisor
Usage: informal; often used in sports or competitive contexts
2. one who is dominant or in charge in a particular situation or group
Usage: informal; slang

Examples

• She's the bosser of the marketing team and makes all the final decisions.
• He acts like the bosser around here, but nobody really listens to him.
• The bosser called a meeting to discuss the new project timeline.
• In that friend group, Maria is definitely the bosser.
• The bosser expects everyone to arrive on time every morning.