In this example sentence:
He needs more time off duty for relaxation and rest.
the Longman dictionary says that off in the given example is an adverb. If the sentence was:
"He needs more time off,"
I would understand that off is an adverb. But in this case, off is followed by a noun, duty. Is this off also an adverb?
5 not at work, school etc because you are ill or on holiday: He needs more time off duty for relaxation and rest.