National Institute of Korean Language in the context of "Revised Romanization of Korean"

Sino-Korean vocabulary or Hanjaeo (Korean: 한자어; Hanja: 漢字語) refers to Korean words of Chinese origin. Sino-Korean vocabulary includes words borrowed directly from Chinese, as well as new Korean words created from Chinese characters, and words borrowed from Sino-Japanese vocabulary. Many of these terms were borrowed during the height of Chinese-language literature on Korean culture. Subsequently, many of these words have also been truncated or altered for the Korean language.

Estimates of the percentage of Sino-Korean ranges from as low as 30% to as high as 70%. According to the Standard Korean Language Dictionary published by the National Institute of Korean Language (NIKL), Sino-Korean represents approximately 57% of the Korean vocabulary.