Defeat; disappointment mixed with acceptance. It is a cute way to express sadness after something unfortunate happens. Word is Japanese in origin.
Nyoro~n originated in a spinoff comic strip called "Nyoron☆Churuya-san" by Utsura Urarak, based on the character of Tsuruya from the anime "The Melancholy of Haruhi Suzumiya". The strip was later expanded into 13 two-minute episodes which are available on youtube by searching "Nyoro~n Churuya-san"; Watching one of these episodes is the best way to understand, through context, what the word means.
Nyoro~n is said in a cute, sad tone of voice after something unfortunate happens. The character who says it is a cute little girl who constantly fails to achieve what she sets out to do (often her goal is to get some smoked cheese).
People who use this word are probably either fans of the Haruhi series and its spinoff, or trying to look really cute, or both.
Try to get change from a vending machine.
It gives all pennies.
"Nyoro~n"
Set out for a picnic.
It starts to rain.
"Nyoro~n"
You eat the food in the rain anyway.
You: Hello Best Friend, I got you some smoked cheese for your birthday!
Best Friend: I am lactose intolerant.
You (crestfallen): Nyoro~n...
You: Don't worry, I'll get you something even better, then!
Best Friend: But there is nothing better than smoked cheese.
You (realizing they are right): Nyoro~n...
plutonian nyborg is a fictional drug seen in the classic 1981 animated feature film "Heavy Metal". the drug is an inhaled white powder whose appearance resembles cocaine, and whose effects resemble those of marijuana; used by two alien starship pilots Edsel and Zeke, seen in the segment of Heavy Metal entitled "So Beautiful and So Dangerous".
Noboru Yamaguchi was a Japanese light novel and game scenario author from Ibaraki Prefecture, Japan. He was well known for being the author of The Familiar of Zero light novels and visual novels by Frontwing.