Sơn

Sơn is also used as a feminine given name in Vietnamese. Variants of this name used for both genders are San and Sang. However, Sơn is more common for males. So, I think that the "Gender" of this name should be changed from "Masculine" to "Masculine & Feminine".

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Sources: https://forebears.io/forenames/son
https://www.gpeters.com/names/baby-names.php?name=Son