(sometimes italics) (used with a plural verb) the official papers, documents, or other items that prove authenticity, legitimacy, etc., as of a person or enterprise; credentials:
All our bona fides are on file with the SEC.
Can be confused
bona fide, bona fides (see usage note at the current entry)
Bona fides is originally a Latin phrase meaning “good faith.” Fides is singular in Latin and has been used as such in English. At least partially because its -es ending makes bona fides look and sound like a plural, it has developed the plural sense “credentials.” This plural use, although criticized by some usage guides, has been increasing in recent decades in all varieties of speech and writing.