obiism vs necromancy

obiism and necromancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
obiism	Yes	No	No	No
necromancy	Yes	No	No	No

As nouns, necromancy is a hypernym of obiism; that is, necromancy is a word with a broader meaning than obiism:

obiism: belief in a kind of sorcery that originated in Africa and is practiced in the West Indies
necromancy: the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world

Other hypernyms of obiism include black art, black magic, sorcery.

obiism (noun)	necromancy (noun)
belief in a kind of sorcery that originated in Africa and is practiced in the West Indies	conjuring up the dead, especially for prophesying
	the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world