anancasm vs obsession

anancasm and obsession both are nouns.

Word	Noun	Adjective	Verb	Adverb
anancasm	Yes	No	No	No
obsession	Yes	No	No	No

As nouns, obsession is a hypernym of anancasm; that is, obsession is a word with a broader meaning than anancasm:

anancasm: An obsolete term for ritualistic act or sequence of acts performed by a person with obsessive-compulsive neurosis.
obsession: an unhealthy and compulsive preoccupation with something or someone

Other hypernyms of anancasm include fixation.

anancasm (noun)	obsession (noun)
An obsolete term for ritualistic act or sequence of acts performed by a person with obsessive-compulsive neurosis.	an unhealthy and compulsive preoccupation with something or someone
	an irrational motive for performing trivial or repetitive actions, even against your will