tough vs hard-bitten

tough is a noun but hard-bitten is not a noun.

Word	Noun	Adjective	Verb	Adverb
tough	Yes	Yes	No	No
hard-bitten	No	Yes	No	No

tough (noun)	hard-bitten (noun)
an aggressive and violent young criminal
a cruel and brutal fellow
someone who learned to fight in the streets rather than being formally trained in the sport of boxing

tough (adjective)	hard-bitten (adjective)
resistant to cutting or chewing	tough and callous by virtue of experience
physically toughened
not given to gentleness or sentimentality
unfortunate or hard to bear
substantially made or constructed
feeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')
violent and lawless
very difficult; severely testing stamina or resolution
making great mental demands; hard to comprehend or solve or believe