mountain ridge, mountain peak
岺 centers on a high, narrow part of a mountain: a ridge or peak. Both meanings describe the topmost or crest-like shape of a mountain.
岺 combines 山 (mountain) with 令, which likely contributes a phonetic element. The character expresses a mountain ridge or peak.
A mountain 山 with a commanding 令 (order) on top: the peak orders the ridge to rise high.
For レイ, picture a ray of sunlight hitting the mountain ridge at dawn: ray -> レイ, and the peak glows.
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