English Reference
Idiom idiom

bona fide

C1 Roman origin
Meaning

Genuine and honestly meant — the real thing, not a pretence.

Examples
SIMPLE

“It was a bona fide offer, not a joke.”

CONTEXTUAL

“The discount is open to any bona fide student with a current enrolment card.”

COMPLEX

“Establishing that the buyer was bona fide decided the case, because a purchaser who paid a fair price with no notice of the earlier claim takes good title however badly the seller behaved.”

Origin

Bona fides — good faith — was not a decoration in Roman law but a working standard. A whole class of contracts, including sale, hire, partnership and agency, were bonae fidei: the judge was instructed to decide not by the strict letter of what was written but by what good faith required between the parties. It was the mechanism by which Roman law kept up with commercial reality.

Bona fide is the ablative form, meaning in good faith, and English borrowed it as an adjective. A bona fide purchaser is one who bought honestly and without notice of anyone else's claim — still a live category in property law today.

Ordinary English has loosened it to mean simply genuine: a bona fide offer, a bona fide expert. The plural noun bona fides went its own way and now means credentials — the evidence that someone is what they claim.

The Law's Latinconnected storiesSee all Roman origin →

Roman legal Latin that never left the courtroom — or the boardroom.

  1. 01

    caveat emptor (idiom)

    Let the buyer beware — checking what you are buying is your own problem.

    What Rome did not actually say.
  2. 02

    quid pro quo (idiom)

    Something given in return for something else, usually as an understood trade.

    From the apothecary's substitute.
  3. 03

    de facto (idiom)

    In practice, whatever the official position says.

    The question of fact.
  4. 04

    de jure (idiom)

    According to the law, whether or not that is what actually happens.

    The question of law.
  5. 05

    ipso facto (idiom)

    By that very fact — the consequence follows automatically, with no further step.

    Consequences that need no hearing.
  6. 06

    the status quo (idiom)

    The way things currently are, especially when someone wants to keep them that way.

    In statu quo ante bellum.

Last updated August 3, 2026