monolingual vs worker

monolingual and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
monolingual	Yes	Yes	No	No
worker	Yes	No	No	No

As nouns, worker is a hypernym of monolingual; that is, worker is a word with a broader meaning than monolingual:

Other hypernyms of monolingual include actor, doer.

monolingual (noun)	worker (noun)
a person who knows only one language	sterile member of a colony of social insects that forages for food and cares for the larvae
	a person who works at a specific occupation
	a member of the working class (not necessarily employed)
	a person who acts and gets things done

monolingual (adjective)	worker (adjective)
using or knowing only one language