The best girl you’ll ever meet. She’s kind, loving, loyal and will always be there for you. She has a big heart and will always make you laugh and put a smile on your face. You’re a lucky person if you get the chance to meet her.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.