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肖 supplies the sound exactly: xiāo → xiāo.
肖 is
小 small + ⺼ flesh — 'a small piece of the parent's body,' meaning 'to resemble' (
肖像 portrait). Same phonetic family:
消 to extinguish,
销 to melt,
削 to whittle,
霄 sky-vault. Carries a faint 'diminishing light' flavour, fitting the dimming hours.
