a terminal is when a male develops an erection which serves no purpose or which was not desired.
The terminal has no function, it is a random occurrence which usually results in frustration and a desire for it to cease.
The most likely place for a terminal to occur is in a public place where dealing with the terminal is impractical or frowned upon, thereby causing the sufferer to wait it out.
whilst sitting in class, John developed a terminal, and for the duration of the class had to wait it out.
"lou, ive got a terminal, i dont know what to do!"
"you are just going to wait it out, John!"