alienist vs head-shrinker

alienist and head-shrinker both are nouns.

Word	Noun	Adjective	Verb	Adverb
alienist	Yes	No	No	No
head-shrinker	Yes	No	No	No

As nouns, head-shrinker is a hypernym of alienist; that is, head-shrinker is a word with a broader meaning than alienist:

alienist: a psychiatrist and specialist in the legal aspects of mental illness
head-shrinker: a physician who specializes in psychiatry

Other hypernyms of alienist include psychiatrist, shrink.

alienist (noun)	head-shrinker (noun)
a psychiatrist and specialist in the legal aspects of mental illness	a savage who cuts off and preserves the heads of enemies as trophies
	a physician who specializes in psychiatry