thoái

Thoái is a Vietnamese Sino-Vietnamese morpheme derived from the Chinese character 退, meaning retreat, withdraw, or regress. In contemporary Vietnamese it is mainly used as a bound morpheme in compound terms rather than as a stand‑alone verb in everyday speech. Its core sense is retreat or decline, applied across domains such as politics, medicine, and general description of deterioration.

In usage, thoái appears most often in established terms. Common examples include thoái hóa, which denotes degeneration or deterioration of tissues, organs, or cells (also written thoái hoá in some spellings); thoái vị, meaning abdication of the throne or retirement from office; and thoái lui, referring to retreat or withdrawal, especially in military or strategic contexts. The sense of decline can also be extended to describe aging processes or progressive loss of function in systems or structures.

As a standalone word, thoái is relatively rare in modern ordinary language and tends to be found in formal, historical, or scientific contexts. It is typically combined with nouns or adjectives to specify the field of decline or retreat, such as thoái hóa khớp (degenerative joint disease) or thoái hóa não (neurodegeneration). In many uses, the meaning hinges on the accompanying term, but the overarching notion remains retreat, decline, or deterioration.

See also: thoái hóa, thoái vị.