From Longman Dictionary of Contemporary Englishmettlemet‧tle /ˈmetl/ noun [uncountable] 1 BRAVEcourage and determination to do something even when it is very difficulttest/show/prove your mettle a crisis which will test the minister’s mettle2 → on your mettle
Examples from the Corpus
mettle• Frazer's disciple, Malinowski, was of a very different mettle.• He was an outstanding fighter pilot who proved his mettle in a variety of tough assignments, including two wars.• It is in the treatment of the upper torso that the artist really shows his mettle.• Houston is the only team with proven playoff mettle.• Louis Armstrong and Bunny Berigan may have been trumpet talents of a similar mettle but there the resemblance stopped.• The result is a sort of upscale Hemingway-esque story about affluent, pampered men testing their mettle.• You are pleased with yourself for venturing, testing your mettle.test/show/prove your mettle• Townsend boys got into City almost automatically; they had already proved their mettle.• The result is a sort of upscale Hemingway-esque story about affluent, pampered men testing their mettle.• It is in the treatment of the upper torso that the artist really shows his mettle.• Graham led a lovely rib, slabby and clean, though it didn't test our mettle too severely.• Crises will strew his path to test his mettle.• You are pleased with yourself for venturing, testing your mettle.• He was an outstanding fighter pilot who proved his mettle in a variety of tough assignments, including two wars.Origin mettle (1500-1600) metal