Derived from Boni. According to B. Zuanella, it is a surname present in Liessa since the second half of the 19th century, originating from the frazione of Masarolis (municipality of Torreano). The oldest form, Bunin, has been preserved to this day, for example in Montefosca, and in the past it was also present in Biacis di Pulfero (1616) and Vernasso (1682). The surname Bonin (of which Bunin is only a dialectal variant) could derive from the hagionym Bon(ifatius), but the author prefers to derive it directly from the Friulian adjective bon (= good) with the diminutive suffix -in (bon + -in = bonin). This surname is characteristic of Masarolis/Mažaruola, a village situated in the multilingual municipality of Torreano, where onomastic interferences are common. The same reasoning holds for the surname Bonaz/Bonac, also typical of Masarolis, arisen from the base bon with the Slovenian dialectal suffix -ac (-ec); and for Bonig/Bonič, present in the 17th century in Azzida, a patronymic with the Slovenian suffix -ič. The surname Bon is still very widespread today in Friuli. The form Bonini arose from the Latin usage in the parish books, where surnames were sometimes put in the genitive (e.g. 'Lucas filius Antonii Bonini'), a form that, although erroneous, ended up being officially registered.