pontifical vs portentous

pontifical is a noun but portentous is not a noun.

Word	Noun	Adjective	Verb	Adverb
pontifical	Yes	Yes	No	No
portentous	No	Yes	No	No

As adjectives, pontifical and portentous are synonyms defined as:

Other synonyms of pontifical include grandiloquent, overblown, pompous.

pontifical (noun)	portentous (noun)
the vestments and other insignia of a pontiff (especially a bishop)

pontifical (adjective)	portentous (adjective)
denoting or governed by or relating to a bishop or bishops	puffed up with vanity
proceeding from or ordered by or subject to a pope or the papacy regarded as the successor of the Apostles	ominously prophetic
puffed up with vanity	of momentous or ominous significance