mettle Definition

mettle
noun

literary:
1. Courage, determination and endurance.

Thesaurus: spirit, spunk, pluck, vitality, energy, vigor; boldness, daring, bravery, courage, nerve, grit, fortitude; resolve.
2. Character; personal qualities.

Example: show one's mettle

Idiom: put someone on their mettle

literary
To encourage or force them to make their best effort.

Etymology: 16c: originally a variant of metal.