grievous vs severe

grievous and severe both are adjectives.

Word	Noun	Adjective	Verb	Adverb
grievous	No	Yes	No	No
severe	No	Yes	No	No

As adjectives, grievous and severe are synonyms defined as:

Other synonyms of grievous include dangerous, grave, life-threatening, serious.

grievous (adjective)	severe (adjective)
causing fear or anxiety by threatening great harm	causing fear or anxiety by threatening great harm
shockingly brutal or cruel	intensely or extremely bad or unpleasant in degree or quality
of great gravity or crucial import; requiring serious thought	severely simple
causing or marked by grief or anguish	very strong or vigorous
	very bad in degree or extent
	unsparing and uncompromising in discipline or judgment