open, sun
昜 centers on openness and brightness: the sun shining openly, or something spread out and unobstructed.
昜 is thought to combine 旦 (sunrise) with 勿 (a flag or pennant), suggesting the sun spreading its light openly like an unfurled banner. The exact historical development is uncertain, but the component combination is consistent with the meanings of openness and sunlight.
The top 旦 shows the sun rising above the horizon, and the bottom 勿 looks like a flag unfurling in the morning light. Together they picture the sun spreading its rays openly across the sky.
For ヨウ, imagine the sun yawning open at dawn: yawn -> ヨウ, and the sunlight spreads out like an open yawn.
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