A reddish glow or flush appearing on the face, usually caused by shyness, embarrassment, or intoxication.

A phenomenon where an algal bloom causes seawater to turn red or brown, often depleting oxygen and harming marine life; also known as 赤潮 chì​cháo.

A literary or indirect term for a woman's menstrual period, named for its regular cycle like the rising and falling of a tide; also known as 天癸 tiān​guǐ.