forbidding vs sinister

forbidding is a noun but sinister is not a noun.

Word	Noun	Adjective	Verb	Adverb
forbidding	Yes	Yes	No	No
sinister	No	Yes	No	No

As adjectives, forbidding and sinister are synonyms defined as:

forbidding and sinister: threatening or foreshadowing evil or tragic developments

Other synonyms of forbidding include baleful, menacing, minacious, minatory, ominous, threatening.

forbidding (noun)	sinister (noun)
an official prohibition or edict against something

forbidding (adjective)	sinister (adjective)
threatening or foreshadowing evil or tragic developments	threatening or foreshadowing evil or tragic developments
harshly uninviting or formidable in manner or appearance	stemming from evil characteristics or forces; wicked or dishonorable
	on or starting from the wearer's left