river in Sichuan province
涪 is a specific proper noun referring to a river in Sichuan province. Its meaning is limited to this geographical name.
涪 combines the water radical 氵 with the phonetic component 咅, forming a character used primarily as a river name. The exact historical development is uncertain beyond this phono-semantic structure.
The water radical 氵 beside 咅 suggests a river. Picture the 咅 component as a marker for the Fu River in Sichuan, with water flowing beside it.
For フウ, imagine a strong wind (風, ふう) blowing across the Fu River: 風 -> フウ, and the river's name echoes the sound of the wind.
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