cornerstone vs explanation

cornerstone and explanation both are nouns.

Word	Noun	Adjective	Verb	Adverb
cornerstone	Yes	No	No	No
explanation	Yes	No	No	No

cornerstone (noun)	explanation (noun)
a stone at the outer corner of two intersecting masonry walls	thought that makes something comprehensible
a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies	a statement that makes something comprehensible by describing the relevant structure or operation or circumstances etc.
the fundamental assumptions from which something is begun or developed or calculated or explained	the act of explaining; making something plain or intelligible