firmness

(noun) the muscle tone of healthy tissue. Synonyms: soundness. Example: "His muscular firmness."

(noun) the trait of being resolute. Synonyms: resoluteness, firmness of purpose, resolve, resolution. Examples: "His resoluteness carried him through the battle." "It was his unshakeable resolution to finish the work."

(noun) the property of being unyielding to the touch.

(noun) the quality of being steady or securely and immovably fixed in place. Synonyms: steadiness.