nerve

nouns

any bundle of nerve fibers running to various organs and tissues of the body
nerve, nervus
is derived from
nervous
the courage to carry on
"he kept fighting on pure spunk"; "you haven't got the heart for baseball"
heart, mettle, nerve, spunk
is derived from
nervy
impudent aggressiveness
"I couldn't believe her boldness"; "he had the effrontery to question my honesty"
boldness, brass, cheek, face, nerve
is derived from
nervy

verbs

get ready for something difficult or unpleasant
nerve, steel