Sino-Vietnamese vocabulary (Vietnamese: từ Hán Việt, Chữ Hán: 詞漢越, literally 'Chinese-Vietnamese words') is a layer of about 3,000 monosyllabic morphemes of the Vietnamese language borrowed from Literary Chinese with consistent pronunciations based on Middle Chinese. Compounds using these morphemes are used extensively in cultural and technical vocabulary. Together with Sino-Korean and Sino-Japanese vocabularies, Sino-Vietnamese has been used in the reconstruction of the sound categories of Middle Chinese. Samuel Martin grouped the three together as "Sino-xenic". There is also an Old Sino-Vietnamese layer consisting of a few hundred words borrowed individually from Chinese in earlier periods. These words are treated by speakers as native words. More recent loans from southern Chinese languages, usually names of foodstuffs such as lạp xưởng 'Chinese sausage' (from Cantonese 臘腸; 腊肠; laahpchéung), are not treated as Sino-Vietnamese but more direct borrowings.[1]
Estimates of the proportion of words of Sinitic origin in the Vietnamese lexicon vary from one third to half and even to 70%.[2][3][4] The proportion tends towards the lower end in speech and towards the higher end in technical writing.[5] In the famous Từ điển tiếng Việt dictionary by Vietnamese linguist Hoàng Phê, about 40% of the vocabulary is of Sinitic origin.[6]