Not used alone in modern Chinese; it survives in literary words — 粲然 (beaming brightly) and 以博一粲 (to raise a smile). It shares its sound with 灿 (brilliant) and 璨 (gleaming), and the bottom is the grain radical 米.
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Literary only; everyday Chinese uses 灿烂 for 'brilliant' and 笑 for 'smile'.