Can't look away? That's because something spellbinding grabs your interest and holds it: you're so fascinated with it that it feels almost like magic.
You may find your favorite movie or a moving piece of music spellbinding, while to your science-loving friend, the biology teacher's lecture is spellbinding. If your attention is really held by something—almost as if a magical spell is tying or binding it there—that thing is spellbinding. Spellbinding things are mesmerizing, captivating, or enchanting.