A heavy-weight thread of execution in UNIX and UNIX-like operating systems, possessing it's own process id, code, data, initialized data, file descriptors, etc. As opposed to a thread or light-weight process (LWP). Primarily refers to user privilege threads, as opposed to "kernel processes" or "kernel threads" which run with supervisor (or superuser) privileges.
A running program in a multitasking operating system.
The result of the fork() system call in UNIX-based operating systems.
