maさおsaoまっmaさおsao
1.

Describes something that is distinctly blue, devoid of any other color, as seen in a clear sky or ocean.

2.

Indicates a state of pallor or extreme paleness, often associated with fear or shock, suggesting a noticeable loss of color from one's face.

Example:

これをきいたとたん、彼は真っ青になった。