Clipping of initialization.
"The system uses init to start all processes, a term that is simply clipping of initialization."
"The init process is responsible for starting up all other programs on your computer when you turn it on."
Clipping of initialize.
"The system administrator ran init to start all the services after rebooting the server."
Alternative form of innit.
"He asked if that was true, and I just replied init."
The word init is a clipped form derived from the longer words initialize and initialization. It entered English usage as a convenient shorthand to refer specifically to the process of starting up a program or system.