convulsion vs clonus

convulsion and clonus both are nouns.

Word	Noun	Adjective	Verb	Adverb
convulsion	Yes	No	No	No
clonus	Yes	No	No	No

As nouns, clonus is a hyponym of convulsion; that is, clonus is a word with a more specific, narrower meaning than convulsion:

convulsion: violent uncontrollable contractions of muscles
clonus: convulsion characterized by alternating contractions and relaxations

Other hyponyms of convulsion include epileptic seizure.

convulsion (noun)	clonus (noun)
a physical disturbance such as an earthquake or upheaval	convulsion characterized by alternating contractions and relaxations
violent uncontrollable contractions of muscles
a sudden uncontrollable attack
a violent disturbance