Definition of "Seelie"

Okay, so that sounded like the Seelie hated the Unseelie and vice versa. But not quite. There was something more here. I puzzled over it several moments. Did it mean the Seelie couldn't actually touch the Unseelie, and vice versa? I read on.

2008, Karen Marie Moning, Faefever: Fever Series, Delacorte Press

We like the Seelie court and the humans lived, loved and laughed. As the war between the Seelie and the Unseelie escalated and the Seelie gained the upper hand we Unseelie were forced to hide in the shadows and fear for our lives.

2015, Selena Thana, Sidhe Megalomania: Tuath Dé - Tome 4, K. George

“Like Sleeping Beauty, you mean,” I said. Henry nodded. His handsome face was very worried, and I didn't know him long enough to read him that well. “They came and saw the garden, and it was very Seelie, my lord. More than that, none.”

2008, Laurell K. Hamilton, Swallowing Darkness: A Novel, Ballantine Books

“Altruism is very Seelie.” “The sidhe were all Seelie once,” Shock said. “Either we resign ourselves to that part of our history or we go mad. I do not fight my impulses toward love and beauty the way my father does. But enough of that.”

2018, Mishell Baker, Impostor Syndrome, Simon and Schuster