contract vs convulse

contract is a noun but convulse is not a noun.

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

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

Other hyponyms of contract include choke, strangle, prim, astringe, strangulate, bear down, overbear, choke, fret, gag, choke, scrag.

contract (noun)	convulse (noun)
a variety of bridge in which the bidder receives points toward game only for the number of tricks he bid
a binding agreement between two or more persons that is enforceable by law
(contract bridge) the highest bid becomes the contract setting the number of tricks that the bidder must make

contract (verb)	convulse (verb)
be stricken by an illness, fall victim to an illness	be overcome with laughter
make or become more narrow or restricted	make someone convulse with laughter
become smaller or draw together	contract involuntarily, as in a spasm
reduce in scope while retaining essential elements	cause to contract
compress or concentrate	move or stir about violently
enter into a contractual arrangement	shake uncontrollably
make smaller
squeeze or press together
engage by written agreement