Question 1

What does "a feather in one's cap" mean?

Accepted Answer

An achievement or accomplishment that one can be proud of.

Question 2

How do you use "a feather in one's cap" in a sentence?

Accepted Answer

Winning the national award was a real feather in her cap.

Question 3

Is "a feather in one's cap" formal or informal?

Accepted Answer

"a feather in one's cap" is register-neutral — appropriate in both casual and formal contexts. Derived from the practice of adding feathers to hats as marks of honour; still widely used today.