Hack Code

I don't talk about hacking the code.  

Hack is the source code of the program to solve the problem which can't be solved by the software. 

For an instance, When process1 code is under implementation which sends data to process2, process2 code can be hardcoded to get the proper output. By this way, process2 code no need to wait for process1 code to be committed to do the verification. It doesn't originally solve the problem, but it is. 

Hence, hack refers to writing a small program or adding code to an existing program to solve the problem in a hurry. True hackers go far beyond the skill and understand the intricacies of the system. 

Reference: pcmag.com