A german chess word meaning time pressure, or literally "time emergency". If you are playing a timed chess game and you are very close to having used up your entire allowed time for the game, you have a zeitnot on your hands.
The distinct melancholy or mourning one may experience when thinking about the potential pasts, presents, and futures one may have experienced had they made different decisions in their life; a negative reaction to the endless stream of possibilities and 'what if's one accumulates throughout their lifetime
"Dude, I've been thinking about how my life could be right now if I did get together with that one girl from school, and now I'm super bummed."
"That's just Zeitenschmerz for you."
All the guys want to be him, all the ladies want to be with him. Smart, confident, charming, he'll even take your mom out for dinner. If you meet a Zeth, you will NEVER forget it.