Concept

Wei-defensive qi

卫气wei qi

2 sources

In Chinese medicine, the defensive qi: a fierce, swift qi that travels outside the vessels through the limbs, flesh and skin without rest, warming and protecting the exterior. The Neijing states it moves in the yang by day and the yin by night, and is paired with, and opposite to, ying-nutrient qi.

Source

Huangdi Neijing (Inner Canon of the Yellow Emperor)《灵枢·邪客》（内经选读下篇·藏象·气血营卫·原文2207）

References

《内经》本神/决气/邪客等综合理解（德气生精神魂魄意志思虑智认知层级链 / 营卫宗气津液生成运行）
WHO IST-TCM 2022 术语对齐（WGM2# 240）

Full definition

Classical source text (Chinese) — English summary above.

衛氣者，出其悍氣之慓疾，而先行於四末分肉皮膚之間而不休者也

Citations

Huangdi Neijing (Inner Canon of the Yellow Emperor) · 托名黄帝/岐伯（先秦—西汉医家辑） · 《灵枢·邪客》（内经选读下篇·藏象·气血营卫·原文2207）Cited from Huangdi Neijing (Inner Canon of the Yellow Emperor) for its definition.
WHO international standard terminologies on traditional Chinese medicine · World Health Organization · WHO IST-TCM 2022, WGM2# 240 (§1.4 精气血津液类)Cited from WHO international standard terminologies on traditional Chinese medicine for its standardized terminology.