This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 嵟 is uncertain. It visually combines 屵 (a cliff or mountain-related shape) with 隹 (a bird), but the original semantic or phonetic role of these components is unclear.
With no clear meaning, picture a rare bird (隹) perched on a high cliff (屵) — a scene that is hard to interpret, just like this kanji.
For キ, imagine a key (キー) unlocking the mystery of this rare cliff-bird kanji: key -> キ.