涑 has no general meaning in modern Chinese; it exists almost only in the river name 涑水 in Shanxi. The Song historian Sima Guang took his style name 涑水先生 from this river.
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Proper-noun only — you will only meet 涑 in maps and old geography, never in everyday vocabulary.
Right side 束 (to bind) is the sound element; the reading shifted slightly from shù to sù. It supplies no 'binding' meaning here — it is a pure phonetic tag in this river name.
