Uncertain. Some sources derive this from the dialectalArabicبُوزَقّ(būzaqq,“someone with a belly”), fromبُو(bū,“someone with”) +زَقّ(zaqq,“belly”). The semantic shift is explainable due to the container's characteristic shape, comparebuzzicone(“fat person”), which seemingly retained the original meaning. Anyhow most certainly akin tobuzzo(“fat, belly”). The voiceless/ts/ instead of/dz/ is likely due to influence of the other senses.
