Giới thiệu một giả thuyết về từ thuần Việt his paper deals with the concept ofVietnamese native words. Opinions ofVietnamese linguists differ with regards to what is considered a Vietnamese native word. In the pinion ofauthor ofthis paper, the origins ofwords are important in defming Vietnamese native words though this way faces many difficulties. Moreover the concept of Vietnamese native word should be considered in its movement and evolution. Also distinction between foreign and loan words should be made. Only loan words which preserve their foreign features are considered foreignism, whiledeeply Vietnamized words can be considered Vietnamese native words. That is why it is helpful to defme and apply concepts ofsynchronic Vietnamese native word and synchronic foreignism.