This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 嶊 is uncertain. It combines 山 (mountain) with 推, but the original semantic and phonetic roles are unclear.
The top is 山 (mountain) and the bottom is 推 (push). Imagine a mountain pushing up from the earth, but its meaning remains unclear.
For スイ, picture a mountain so steep it makes you sweat (スイ from スイート sweat, but pronounced like 'swee'). The mountain pushes you to sweat.
—