imprimatur vs indorsement

imprimatur and indorsement both are nouns.

Word	Noun	Adjective	Verb	Adverb
imprimatur	Yes	No	No	No
indorsement	Yes	No	No	No

As nouns, imprimatur and indorsement are synonyms defined as:

Other synonyms of imprimatur include countenance, endorsement, sanction, warrant.

imprimatur (noun)	indorsement (noun)
formal and explicit approval	the act of endorsing
	formal and explicit approval
	a promotional statement (as found on the dust jackets of books)
	a speech seconding a motion
	a signature that validates something