sign vs communicate

sign is a noun but communicate is not a noun.

Word	Noun	Adjective	Verb	Adverb
sign	Yes	Yes	Yes	No
communicate	No	No	Yes	No

As verbs, communicate is a hypernym of sign; that is, communicate is a word with a broader meaning than sign:

Other hypernyms of sign include intercommunicate.

As verbs, communicate is a hypernym of sign; that is, communicate is a word with a broader meaning than sign:

Other hypernyms of sign include intercommunicate.

sign (noun)	communicate (noun)
structure displaying a board on which advertisements can be posted
a public display of a message
a gesture that is part of a sign language
any nonverbal action or gesture that encodes a message
a character indicating a relation between quantities
a perceptible indication of something not immediately apparent (as a visible clue that something has happened)
a fundamental linguistic unit linking a signifier to that which is signified
an event that is experienced as indicating important things to come
(astrology) one of 12 equal areas into which the zodiac is divided
having an indicated pole (as the distinction between positive and negative electric charges)
(medicine) any objective evidence of the presence of a disorder or disease

sign (adjective)	communicate (adjective)
used of the language of the deaf

sign (verb)	communicate (verb)
be engaged by a written agreement	transmit thoughts or feelings
communicate silently and non-verbally by signals or signs	transmit information
mark with one's signature; write one's name (on)	be in verbal contact; interchange information or ideas
make the sign of the cross over someone in order to call on God for protection; consecrate	receive Communion, in the Catholic church
communicate in sign language	administer Communion; in church
place signs, as along a road	join or connect
approve and express assent, responsibility, or obligation	transfer to another
engage by written agreement