- courage and fortitude: a man of mettle.
- disposition or temperament: a man of fine mettle.
- on one’s mettle, in the position of being incited to do one’s best: The loss of the first round put him on his mettle to win the match.
- courage; spirit
- inherent character
- on one’s mettle roused to putting forth one’s best efforts
n.1580s, variant spelling of metal, both forms used interchangeably (by Shakespeare and others) in the literal sense and in the figurative one of “stuff of which a person is made” (1550s) until the spellings and senses diverged early 18c.