Sung
Most often a Korean surname, Sung is a romanized family name that can reflect several different Korean hanja and meanings.
The #4,801 most common surname in the United States (2010 Census) — about 1 in every 41,949 Americans shares it.
Etymology
In Korean, Sung is a romanization of a surname written with different Chinese characters, so the exact original meaning can vary from one family line to another. Because the same spelling can represent more than one hanja, the name is better understood as a Korean clan surname than as a single word with one fixed literal meaning. Older English-language surname books in your excerpts do not provide a real etymology for this specific spelling, so the best-supported explanation is the modern Korean one.
History
As a romanized surname, Sung is chiefly associated with Korean families in Korea and in the Korean diaspora. Its frequency in the United States reflects twentieth-century immigration and later naturalization, along with the use of different romanization systems that can also produce spellings such as Seong.
Origin
Regions
Variant spellings
Fun fact
Because multiple Korean surnames can be romanized as Sung or Seong, the spelling alone does not identify a single ancestral meaning or clan.
From the historical record
“It is natural that many favourite names should be taken from those of heroes of romance whose exploits were sung all over Europe by wandering minstrels. Such names, including those taken from the Round Table legends, usually came to us through French, though a few names of the British heroes are Welsh, e.g. Cradock…”
— The Romance of Names