fall, die
殞 centers on a sudden, often fatal downward motion: falling from a height or dying, especially in a violent or untimely way.
殞 combines 歹 (death, decay) with 員, which likely contributes the sound. The character originally referred to dying or perishing, with the fall sense extending from the idea of dropping dead.
The left side 歹 suggests death or decay, and the right side 員 looks like a person tumbling headfirst. Picture someone falling to their death: 殞 means to fall and die.
For イン, imagine an inn where a tragic fall happens: inn -> イン, and the 歹 (death) radical marks the fatal fall.