A quality of endurance and courage. / Good temperament and character. / (obsolete) Metal; a metallic substance.

(Scotland)

Having mettle or high spirits; ardent.

plural of mettle

Putting forth one's best efforts.

Marked by mettle or bravery; courageous.

The quality of being mettlesome.

A surname. / A census-designated place in Kern County, California, United States.

plural of Mettler

In a mettlesome manner.