mettle
Mettle (noun) means Courage, strength of character, and determination in the face of difficulty. Example: “The rookie proved her mettle during the final, high-pressure match.”
How to use mettle
Learner’s notesIn plain EnglishInner toughness and courage, especially when things get hard.
Don't confuse with metal (the material) — mettle refers only to character and courage.
Fill the gap
Can you complete this real example?
The rookie proved her _____ during the final, high-pressure match.
Etymology
A figurative spelling variant of metal, dating back to the 1500s; the two words were once interchangeable before splitting into separate meanings in the 1700s.