yodan verb with 'mu' ending (archaic), intransitive verb
look daunted; become discouraged
Archaic intransitive verb. Describes a person's expression turning pale or losing spirit when faced with difficulty. The modern equivalent is 鼻白む (はなじろむ), which is also rare but more recognizable.
See also: 鼻白む (はなじろむ)
In old war tales, warriors who look daunted by the enemy's force are depicted.
Compound of 鼻 (nose) and 白む (to become white/pale), referring to the face losing color. The exact historical derivation is uncertain, but the image is of someone turning pale with discouragement.