contract vs sign

contract and sign both are nouns.

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

As verbs, sign is a hyponym of contract; that is, sign is a word with a more specific, narrower meaning than contract:

Other hyponyms of contract include stipulate, condition, qualify, specify, stipulate, lease, rent, charter, hire, lease, rent.

As verbs, contract and sign are synonyms defined as:

Other synonyms of contract include sign on, sign up.

contract (noun)	sign (noun)
a variety of bridge in which the bidder receives points toward game only for the number of tricks he bid	structure displaying a board on which advertisements can be posted
a binding agreement between two or more persons that is enforceable by law	a public display of a message
(contract bridge) the highest bid becomes the contract setting the number of tricks that the bidder must make	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

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

contract (verb)	sign (verb)
be stricken by an illness, fall victim to an illness	be engaged by a written agreement
make or become more narrow or restricted	communicate silently and non-verbally by signals or signs
become smaller or draw together	mark with one's signature; write one's name (on)
reduce in scope while retaining essential elements	make the sign of the cross over someone in order to call on God for protection; consecrate
compress or concentrate	communicate in sign language
enter into a contractual arrangement	place signs, as along a road
make smaller	approve and express assent, responsibility, or obligation
squeeze or press together	engage by written agreement
engage by written agreement