Is mettle a verb or noun?

"Mettle" is primarily a noun. It means courage, spirit, or stamina.

Here are some examples:

* "The soldiers showed great mettle in the face of danger."

* "She has the mettle to succeed in this challenging field."

While "mettle" is not a verb, you might encounter phrases like "to have mettle" or "to show mettle", which use the noun "mettle" in a verb-like way. However, these phrases are still considered idiomatic expressions rather than actual verb forms.