I just stumbled on this Tumblr and already love everything about it. As the author describes, it's “a compendium of invented words written by John Koenig. Each original definition aims to fill a hole in the language—to give a name to emotions we all might experience but don’t yet have a word for.”
His definition for sonder—which he also produced a video for—is the sort of thing I think about all the time:
n. the realization that each random passerby is living a life as vivid and complex as your own—populated with their own ambitions, friends, routines, worries and inherited craziness—an epic story that continues invisibly around you like an anthill sprawling deep underground, with elaborate passageways to thousands of other lives that you’ll never know existed, in which you might appear only once, as an extra sipping coffee in the background, as a blur of traffic passing on the highway, as a lighted window at dusk.
This site speaks to me in so many ways. Such a wonderful concept, beautifully written.