Hunk is the executable file format of tools and programs of the Amiga Operating System based on Motorola 68000 CPU and other processors of the same family. This kind of executable got its name from the fact that the software programmed on Amiga is divided in its internal structure into many pieces called hunks, in which every portion could contain either code or data.
The hunks in an Amiga executable file could exist in various types. There are 32-bit hunks, 16-bit hunks, and even some 8-bit hunks.
Types of hunks were standardized in AmigaOS, and well documented in The AmigaDOS Manual edited by Commodore to explain to programmers how to code on the Amiga, during the years in which Commodore manufactured Amiga computers. Their structure was officially codified and could be changed only by a Commodore committee, which then communicated the modifications to the developers for new releases of the Amiga operating system.
The structure of an Amiga hunk is very simple: There is a header at the beginning of the hunk indicating that that kind of "portion of code" is a known and valid Amiga hunk type, then follows an ID which indicates the length of the hunk itself, and at the bottom is the segment of the hunk which contains the real code or data. (Full article...)