in opposition, distant from, separated
暌 centers on separation and opposition: being distant from something or standing in contrast to it.
暌 combines 日 (sun) with 癸, which likely contributes the sound. The exact historical development of the meaning 'in opposition' or 'separated' is uncertain.
The sun 日 beside 癸 suggests a sundial or shadow that marks separation: when the sun moves, shadows grow distant and opposite.
For ケイ, imagine a kayak (ケイ) drifting away from shore, becoming distant and separated from land.