various place names, surname, transliteration of Sanskrit "u"
鄔 is a rare kanji used mainly as a proper noun: a surname, various historical place names, and a transliteration character for the Sanskrit sound "u". It has no common standalone meaning.
鄔 is a phono-semantic compound with ⻏ (city, place) and 烏 (sound component). It was used in ancient Chinese place names and later as a surname.
The left side 烏 (crow) beside the right side ⻏ (city wall) suggests a place named after crows or a crow-related landmark. Think of it as a specific old place name or surname.
For オ, imagine a crow (烏) perched on a city wall (⻏) letting out a loud "Oh!" sound: Oh -> オ.
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