In a general sense object code is a sequence of statements or instructions in a computer language, usually a machine code language (i.e., binary) or an intermediate language such as register transfer language (RTL). The term indicates that the code is the goal or result of the compiling process, with some early sources referring to source code as a "subject program".
Object code is a portion of machine code that has not yet been linked into a complete program. It is the machine code for one particular library or module that will make up the completed product. It may also contain placeholders or offsets, not found in the machine code of a completed program, that the linker will use to connect everything together. Whereas machine code is binary code that can be executed directly by the CPU, object code has the jumps partially parametrized so that a linker can fill them in.
An assembler is used to convert assembly code into machine code (object code). A linker links several object (and library) files to generate an executable. Assemblers can also assemble directly to machine code executable files without the object intermediary step.
Traditionally, the output of the compilation has been called object code or sometimes an object module.