
Although the derivation of most Bohemian Jewish names are relatively easy to determine, there are a few common names whose origins remain speculative.
Bloch -- Wikipedia gives the commonly assumed derivation, from the Polish word "Włoch" (meaning Italian or stranger). Although oft-repeated, there is no good evidence for this derivation. The variant Wloch or Vloch does not exist either, yet Ploch does. The B/P (as opposed to B/V) variation (seen also in Epstein/Ebstein and Porges/Borges) would seem to point toward a possible derivation from the common name Pollak (meaning Polish), which might explain the widespread use of the name in Bohemia and Alsace.
Bondi -- Assumed to be derived from the Italian for Good Day (equivalent to the common name YomTov). But the evidence for this is slim.
Popper -- Ancestry says "origin uncertain", but suggests it could come from the river Poprad in Slovakia. Another theory is that it relates somehow to Frankfurt (since Feh-Peh are similar Hebrew letters and often switched). A Czech torah scroll from Kostelec nad Orlici (on display at Los Angeles Museum of the Holocaust) contains unusual passages with double-peh letters, a custom known as Osios Meshunos, perhaps relating also to the Popper name.
Taussig -- Assumed (see Ancestry) to derive from the Bohemian town of Taus (Domažlice). The name is far too common to be derived from a small Bohemian town without some other explanation, as in the far-reaching Horowitz rabbinic family (from the town of Horovice).