Wiktionary
pseudoterminal
n. (context computing English) A pair of pseudodevices that can communicate with each other without the hardware that a true device would require.
Wikipedia
Pseudoterminal
In some operating systems, including Unix, a pseudoterminal, pseudotty, or PTY is a pair of pseudo-devices, one of which, the slave, emulates a real text terminal device, the other of which, the master, provides the means by which a terminal emulator process controls the slave.