affidation
/ˌafɪˈdeɪʃn/Now historical
noun
Sworn confirmation of a fact, promise, or obligation; especially sworn confirmation of one's intent to marry.
Origin
Early 17th century; earliest use found in Samuel Daniel (?1563–1619), poet and historian. From post-classical Latin affīdation-, affīdatio solemn promise, declaration on oath, betrothal from affīdat-, past participial stem of affīdare + classical Latin -iō.