high, towering
嶢 centers on extreme vertical height: a mountain that is high and towering, or anything that rises steeply above its surroundings.
嶢 combines 山 (mountain) with 堯, which likely contributes the sound and the idea of height or loftiness. The exact historical development of 堯 is uncertain, but the compound suggests a towering mountain.
A mountain 山 beside the tall, layered shape 堯: imagine a peak so high it towers above the clouds.
For ギョウ, picture a towering mountain that looks like a giant gyōza (ギョウザ) standing on end: gyō -> ギョウ, and the mountain is as high as a stack of dumplings.