1
: good faith : sincerity
2
: the fact of being genuine
—often plural in construction
3
: evidence of one's good faith or genuineness
—often plural in construction
4
: evidence of one's qualifications or achievements
—often plural in construction

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Bona fides looks like a plural word in English, but in Latin it is a singular noun that literally means "good faith." When bona fides entered English, it at first stayed very close to its Latin use, and it also kept its singular form—for example, "a claimant whose bona fides is unquestionable." But in the 20th century, use of bona fides began to widen, and it began to appear with a plural verb in certain contexts, such as "the informant's bona fides were ascertained."

Examples of bona fides in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Canaries in the Coal Mine John Ioannidis is a professor at Stanford University’s medical school and was among the first to question Theranos’s bona fides in a 2015 article. — Mary Randolph, Scientific American, 16 Oct. 2026 The two governors, who mended fences after clashing over last year’s Proposition 50 redistricting campaign, lavished praise on each other for their climate bona fides. — Lia Russell, Sacbee.com, 15 Oct. 2026 Despite her Midwestern appeal, Williams touts her New York bona fides as a product of the neighboring suburbs. — Dan Adler, Vanity Fair, 13 Oct. 2026 Now, Latino politicians must run on their bona fides for all Angelenos, instead of just their latinidad. — Los Angeles Times, 9 Oct. 2026 See All Example Sentences for bona fides

Word History

Etymology

Latin, literally, good faith

First Known Use

1665, in the meaning defined at sense 1

Time Traveler
The first known use of bona fides was in 1665

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Cite this Entry

“Bona fides.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bona%20fides. Accessed 20 Oct. 2026.

Legal Definition

: good faith
the fact that the plaintiff conducted an investigation demonstrated its bona fides—Jeannette Glass Co. v. Indemnity Ins. Co. of North America, 88 A.2d 407 (1952) (dissent)
Etymology

Latin

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