the name comes from two words.
shawol being the fandom name for
shinee fans and ethereal (by google's meaning) "extremely delicate and light in a way that seems not to be of this world" meaning that the shawol is sensitive, easily hurt and the light would refer to
jonghyun. they really love him so he pretty much a part of them. since the word can also be used for jewellery and that's was the theme shinee went for, it made sense to go by this name.
usually it's a new shawol that has a super strong chemistry with
kim jonghyun, a member from shinee, and interacts with him by looking at his videos,
talking to the moon and even gets upset whenever they see funeral pictures of him. however, they could get crazy by crying when they don't see the moon, send letter/calls himself and pretends that it's jonghyun, would buy a cardboard cut-out of him and would use that to do weird acts with him and actively flirts with him, all whilst still in denial that they're in love with him. you may think this is bad but oh boy it gets worse-
(also the gif is what I wanna do to the crazy ethereal shawols)