I've heard theory that it's a place, but have never heard of a place with a similar name...
Adding to what jutky cited:
There is a parenthetical note in Rashi to Judg. 20:45* that after the civil war described there, in which most of the tribe of Benjamin was wiped out, some one hundred members of the tribe fled the Land of Israel and ended up "in the lands of Rome and Germany." Those who remained behind - including Eliyahu (or his ancestors) - came to be called "toshavim," residents (of the Land).
* The source given, מ"ע, is Megaleh Amukos by R' Nosson Nota Shapiro (17th century). This and many other such parenthetical notes first appeared in a 1699 edition of Tanach.
Here is some info about Tishbi.
There is written that it is either a name of city (which has not been identified) or another form the word "תושב"