STY (pronounced "sty", not spelled out) n. A
pseudo-teletype, which is a two-way pipeline with a job on one end and
a fake keyboard-tty on the other. Also, a standard program which
provides a pipeline from its controlling tty to a pseudo-teletype (and
thence to another tty, thereby providing a "sub-tty"). This
is MIT terminology; the SAIL and DEC equivalent is PTY.