Emotionless and stable

phlegmatic
(adj)
fleg-MAT-ic
Meaning

1. sluggish

1st Sample Sentence

1. In northern countries, bears start to become phlegmatic during the autumn, before finally falling into a deep sleep that lasts throughout the winter.

2nd Meaning

2. unexcitable

2nd Sample Sentence

2. Being of a phlegmatic disposition, he almost never gets angry.

Root

phlegma phlegmatos (inflammation, heat, humor caused by heat) (Greek)

Mnemonics

Phlegmatic: phleg (flag) when we hoist a FLAG we have the AUTOMATIC reaction be calm and unexcited. Sounds like PRAGMATIC (practical). Practical people think with logic and show little emotion. If you have lots of phlegm due to cold then you would be unresponsive or impassive due to tiredness.