English
affiant
From affy (“(obsolete) to have faith in, trust; to formally affirm or promise; etc.”) + -ant (suffix forming agent nouns from verbs).
Formed from affy ‘(obsolete) to have faith in, trust’ + -ant
Proto-Indo-European *bʰeydʰ- ‘to convince’
…
Vulgar Latin *fīdāre ‘to trust’
Late Latin affidare ‘to betroth’
Anglo-Norman afier
Middle English affien ‘to have faith, trust’
English affy
Today it means
noun An individual witness whose statement is contained in an affidavit; (generally) an individual who makes a sworn deposition; a deponent.
Language periods are conventional ranges, not dates for this word.
Etymograph / affiant