n. A night when you continually wake up throughout the night, and, though it feels like hours have passed, it is still not morning yet. This often occurs when you have to wake up at a certain time the next morning, and your body keeps waking you up in anticipation.
"I have a 7am flight tomorrow morning, and I'm sure I won't be able to sleep well. Tonight is going to be an eterninight."
by zwdawg May 05, 2008