Definition: thunk

In a PC, to execute the instructions required to switch between segmented addressing of memory and flat addressing. A thunk typically occurs when a 16-bit application is running in a 32-bit address space, and its 16-bit segmented address must be converted into a full 32-bit flat address. On the other hand, if a 32-bit program calls a 16-bit DLL, then the thunk is in the opposite direction: from 32 bit to 16 bit.