Korean and Japanese is sister language basically based on the same Chinese character words. Through extensive interactions in various fields for a long time, the two countries have many similarities in terms of language much more than any other country in the world. Of course, Korea has "Hangul", while Japan has "Kana" as own characters, but they are phonetic characters. More than 80% of Korean and more than 90% of Japanese language derive from Chinese characters words. Surprisingly, 2/3 of the two language share exactly same Chinese character words. That means, if one knows basic educational Chinese characters, one can understand the other language and can communicate easily if only know how to pronounce equivalent words. This book lists approximately 8,800 core Korean words with Japanese and English equivalents including romanized pronunciation. Main entries are in Hangul (Korean alphabet) alphabetically with Chinese characters, if any, followed by romanized Korean pronunciation and parts of speech label. In the second line, the entry’s Japanese equivalents followed by romanized Japanese pronunciation. And, in the third line, the entry’s English equivalents followed by standard American pronunciation. 가정(假定) ga jeong [n] 仮定 katei assumption [əsʌmpʃən] 가정(家庭) ga jeong [n] 家庭 katei home [houm] Korean is written with two different scripts: Hangul and Hanjja (Chinese character). While Hangul is mostly used, Chinese characters must be used in order to clarify meaning and almost 80% of Korean language derives from Chinese characters. Japanese is written with three different scripts: Hiragana, Katakana, and Kanji (Chinese character). Typical Japanese words are written with Hiragana and Chinese characters. Chinese characters must be used since almost 90% of the language derives from Chinese characters. Katakana is usually used to write foreign words other than Chinese.