To define phlegmatic, first, think of the word phlegm, they are closely related, which means a mucus-like-liquid produced in the chest, nose, or throat. The Webster's dictionary refers to the word phlegm to define phlegmatic. Phlegm defines as mucus in the lungs or respiratory passages when a person has the flu, chills, or a cold—bad dieting can also cause phlegm and mucus. I guess because phlegm or mucus is blend, cold, and has no real taste or color to associate with, Phlegm is considers phlegmatic.
Phlegmatic defines as someone who is calm, shows no emotions such as excitement, anger, or vitality other than just being. A person who is completely detach from any form of expression like phlegm or mucus: cold, tasteless, or dull. Phlegmatic is like a fortified object, for instance, a sculpture: forever indifferent—remained as it was carved, permanent, unchanged, dull—nothing more, nothing less.
How to define Phlegmatic:
Think of a soldier standing next to Air Force one waiting on the president of the United States. Usually this sort of guard shows no expression on his/her face whatsoever, he/she is phlegmatic. He/she salutes the president phlegmatically displaying neither displeasure nor enthusiasm.
Phlegmatic is dull, indifferent, unexcited, expressionless, emotionless, affectless, colorless, and unenthusiastic.
My visit to North Bay Village elderly nursing home was phlegmatic, the elderlies showed no enthusiasm. I walked in a room full of seniors, which were quieter than a cemetery. So quite, I could hear their breathing in the room: stuffed nostrils of phlegm and mucus, dull faces, and cold pale motionless stares, they all were phlegmatic to visitors. I haven’t seen my grand father in almost a year, yet his expression was phlegmatic to what I think should have been a happy reunion, but he showed no emotion.