firmness, soundness -- (the muscle tone of healthy tissue; "his muscular firmness")
resoluteness, firmness, firmness of purpose, resolve, resolution -- (the trait of being resolute; "his resoluteness carried him through the battle"; "it was his unshakeable resolution to finish the work")
firmness -- (the property of being unyielding to the touch)
steadiness, firmness -- (the quality of being steady or securely and immovably fixed in place)
(TTS Sound)
