the.com/phlegm

means The thick mucus your throat and lungs produce, especially when you're sick, to trap and clear out irritants and germs.

from From Greek phlegma, meaning inflammation or heat, from phlegein 'to burn.' In ancient Greek medicine, phlegm was one of the four bodily humors (alongside blood, yellow bile, and black bile) believed to govern health and temperament — oddly, despite its fiery root, an excess of phlegm was thought to make a person cold, sluggish, and unemotional, which is exactly where our word 'phlegmatic' comes from.