There are multiple definitions - click on the translation that matches your context.

comprador de boa-fé

substantivo

full

bona fide purchaser

noun

Definitions of bona fide purchaser

English

a person who has bought something for a certain value without any knowledge that the seller may not have sold it in good faith (=honestly)

The claimant was not a bona fide purchaser and thus had no legal standing to challenge the subsequent sale.