common person vs cypher

common person and cypher both are nouns.

Word	Noun	Adjective	Verb	Adverb
common person	Yes	No	No	No
cypher	Yes	No	Yes	No

As nouns, cypher is a hyponym of common person; that is, cypher is a word with a more specific, narrower meaning than common person:

common person (noun)	cypher (noun)
a person who holds no title	a secret method of writing
	a message written in a secret code
	a person of no influence
	a quantity of no importance; thing (object:), singular, negative pronoun; pronoun, thing, singular; quantifier: negative existential
	a mathematical element that when added to another number yields the same number

common person (verb)	cypher (verb)
	make a mathematical calculation or computation
	convert ordinary language into code