password vs countersign

password and countersign both are nouns.

Word	Noun	Adjective	Verb	Adverb
password	Yes	No	No	No
countersign	Yes	No	Yes	No

As nouns, password and countersign are synonyms defined as:

password and countersign: a secret word or phrase known only to a restricted group

Other synonyms of password include parole, watchword, word.

password (noun)	countersign (noun)
a secret word or phrase known only to a restricted group	a second confirming signature endorsing a document already signed
	a secret word or phrase known only to a restricted group

password (verb)	countersign (verb)
	add one's signature to after another's to attest authenticity