How is "mettle" best defined?

"Mettle" is best defined as courage and fortitude, as it refers to a person's ability to handle difficult situations and show resilience in the face of adversity. This term is often used to describe someone's inner strength, character, and determination to persevere despite challenges. It emphasizes the mental and emotional qualities that enable a person to confront obstacles head-on and maintain their resolve.

In contrast, the other definitions do not align with the meaning of "mettle." While a physical object made of metal may sound similar due to the phonetic resemblance, it is completely unrelated to the emotional and psychological context associated with "mettle." Weakness or vulnerability suggests a lack of strength, which directly opposes the concept of having mettle. Lastly, indifference to challenges describes a lack of engagement or concern rather than the courageous and fortitudinous nature embodied by the term. Hence, the definition that captures the essence of "mettle" is that of courage and fortitude.