n. 皮夹

[ noun ]
a pocket-size case for holding papers and paper money
<noun.artifact>

billfold \bill"fold`\ (b[i^]l" f[=o]ld`),
A small, thin, flat container, usually made of leather or
imitation leather, having a pocket of a size just large
enough to hold paper currency and folded over once to fit in
the pocket of one's clothing; it is a type of wallet, but
having fewer compartments than the typical wallet.
[PJC]