unfeeling; imperturbable; stoical
He seems an impassive character, but if you get to know him you'll find that he's really very sensitive and passionate about many things.
in (not)#pati (to suffer, endure) (Latin)
dispassionate, impassive, imperturbable, stoic, stolid
Impassive is a person saying-"I’m Passive (Not Active)", that means he has no feelings, emotions. Passive: inactive hence a person inactive in revealing emotions. zzzz