shiver vs shudder

shiver and shudder both are nouns.

Word	Noun	Adjective	Verb	Adverb
shiver	Yes	No	Yes	No
shudder	Yes	No	Yes	No

As nouns, shiver and shudder are synonyms defined as:

Other synonyms of shiver include chill, frisson, quiver, thrill, tingle.

As verbs, shiver and shudder are synonyms defined as:

As verbs, shiver and shudder are synonyms defined as:

Other synonyms of shiver include thrill, throb.

shiver (noun)	shudder (noun)
a reflex motion caused by cold or fear or excitement	an involuntary vibration (as if from illness or fear)
an almost pleasurable sensation of fright	an almost pleasurable sensation of fright

shiver (verb)	shudder (verb)
shake, as from cold	shake, as from cold
tremble convulsively, as from fear or excitement	tremble convulsively, as from fear or excitement