mortmain vs real property

mortmain and real property both are nouns.

Word	Noun	Adjective	Verb	Adverb
mortmain	Yes	No	No	No
real property	Yes	No	No	No

As nouns, real property is a hypernym of mortmain; that is, real property is a word with a broader meaning than mortmain:

mortmain: real property held inalienably (as by an ecclesiastical corporation)
real property: property consisting of houses and land

Other hypernyms of mortmain include immovable, real estate, realty.

mortmain (noun)	real property (noun)
the oppressive influence of past events or decisions	property consisting of houses and land
real property held inalienably (as by an ecclesiastical corporation)