Kupio
Kupio is a grammatical form found in several South Slavic languages, most commonly Croatian, Bosnian, and Serbian. It is the masculine singular past participle of the verb kupiti, meaning “to buy.” As a past participle, kupio is used in perfect tenses with an auxiliary verb (for example, ja sam kupio knjigu meaning “I bought a book”) and can function adjectivally to describe the subject as having performed the action of buying.
In these languages, kupiti conjugates to form different past participle forms depending on gender and number:
Etymology and cognates indicate a common Slavic root related to purchasing. The verb kupiti traces to Proto-Slavic
Occasionally, kupio may be encountered as a surname in some regions, though it is not widely established