feather in {one's} cap
1
a thing that someone takes pride in, such as an accomplishment, honor, etc.
The origin of the idiom "feather in one's cap" dates back to the medieval era, when knights and soldiers would wear feathers in their helmets as a symbol of their achievements in battle. The more feathers a knight had, the more successful they were considered to be. Today, the idiom is used to describe any accomplishment or success that is considered a source of pride or honor.
- Winning the award was a real feather in her cap.
- The promotion was another feather in his cap after years of hard work.
- Publishing his first novel added a feather to his cap.
- Leading the successful campaign became a feather in the team's cap.
- Her groundbreaking research earned her a feather in her academic cap.