peak, cliff, precipice
岧 centers on a high, steep landform: a peak, cliff, or precipice. The meanings all point to a sharp, elevated rocky feature.
岧 combines 山 (mountain) with 召, which likely contributes the sound. The exact historical development is uncertain, but the mountain component clearly indicates a high place.
A mountain 山 calls 召 you to its peak: the top is a steep cliff or precipice.
For テウ, imagine standing on the peak and shouting 'te-u!' (like 'take you') to the valley below: te-u -> テウ, echoing off the cliff.
—