sibyl vs seer

sibyl and seer both are nouns.

Word	Noun	Adjective	Verb	Adverb
sibyl	Yes	No	No	No
seer	Yes	No	No	No

As nouns, seer is a hypernym of sibyl; that is, seer is a word with a broader meaning than sibyl:

Other hypernyms of sibyl include oracle, prophesier, prophet, vaticinator.

sibyl (noun)	seer (noun)
(ancient Rome) a woman who was regarded as an oracle or prophet	a person with unusual powers of foresight
a woman who tells fortunes	an authoritative person who divines the future
	an observer who perceives visually