This paper aims to show, through a diachronical study, how concepts imported from Western civilization were named in South-East Asia, through the help of dictionaries and a huge database of ancient Japanese and Korean texts. This study is part of a research project specializing on Korean, Japanese and Chinese neology. The terminology used in this study is indissociable from the sociopolitical context. Neology, first introduced by the missionaries in the 17th century and continued in the 19th century, led to the creation of religious as well as scientific terms. However, for the sake of modernization, it is Japan who contributed the most to scientific neology, first through its contact with the Dutch, and more thoroughly at the period of “the Opening” to the West at the end of the 19th Century. In addition to Japan, other countries followed a parallel evolution in the creation of neologisms using the same processes of lexical creation, but to lesser extents, especially for religious terms and words related to everyday life. However, for scientific terms, the Chinese, Koreans and Vietnamese borrowed heavily from the Japanese, via translation or retranslation of Western works translated into Japanese.The abandonment of Chinese words in favor of Japanese neologisms not only by the Koreans but also by the Chinese themselves, and the preference of the Japanese for phonetic loans can be attributed to the defeat of China in the Sino-Japanese War (1895) as well as by the innovative and attractive nature of Japanese neologisms. Ultimately, for the sake of linguistic identity, the Chinese, and especially the Vietnamese after 1919, conceived their own neologisms.