Definition: Given the Question and Answer pair, detect whether the answer is acceptable or not. Denote acceptable answer as "yes", otherwise denote as "no". An acceptable answer is consistent with the context in question, detailed, long, and uses general knowledge of English. Answers that are not definite and suggest a variety of options are not acceptable answers.
Input: Question: Somehow I am compelled to use the word "metal" to describe strong "intestinal fortitude", and perseverance however I can't find the spelling or any synonym like this. Does a word that sounds like "metal" exist when describing an individual's character? I'm looking for modern or historic usage of the word. 
Answer: Mettle Defined by Oxford Dictionaries as: a person's ability to cope well with difficulties; spirit and resilience. It is commonly seen in the phrase: (put someone) on their mettle meaning, (of a demanding situation) test someone's ability to face difficulties. 'there were regular public meetings where local MPs were put on their mettle and remorselessly pilloried' Source: ODO Other constructions are possible too, for example: test their mettle, apparently an American version (thanks, @PeterCordes) show your mettle, etc. Origins According to Merriam-Webster, mettle was, as @Sparhawk points out in the comments, originally simply a variant spelling of the word metal (which dates to at least the 13th century), and it was used in all of the same senses as its metallic relative. Over time, however, mettle came to be used mainly in figurative senses referring to the quality of someone's character, with a first known usage in 1581. Today, both words can mean "vigor and strength of spirit or temperament," but only metal is used of metallic substances.

yes