Proper noun
(informal, colloquial) Synonym of Qinghai Lake (as found in English, from sources in China)
(informal, colloquial) Synonym of Yellow Sea; Ellipsis of West Korea Sea. (as found in English language material from Korea)
(informal, colloquial) Synonym of South China Sea; Ellipsis of West Philippine Sea. (as found in English language material form the Philippines)
(informal, colloquial) Synonym of Sea of Japan (as found in English, from sources in Japan)
Source: en.wiktionary.org