Word that sounds like "metal" but means "grit", "tenacity", and "perseverance" [closed]

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.

Solution 1:

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.

Solution 2:

Steely - (Of a person, his qualities, etc) Hard and cold as steel, unimpressionable, inflexible, obdurate (OED).