Green’s Dictionary of Slang

hack v.2

[SE hack, to chop]

1. [late 19C+] (also hack off, hell-hack) to irritate, to annoy.

2. [20C+] (US campus) to tease gently.

3. [1970s+] (orig. computing) to tinker with a computer system for pleasure and as a proof of one’s expertise.

4. [1980s+] (orig. computing) to gain unauthorized access to a computer system (and poss. use that access for illegal activities).

5. [2010s] se sense 3 or 4 but with systems other than computers.