unemotional
apathetic
calm
cool
disciplined
dispassionate
emotionless
frigid
impassive
imperturbable
indifferent
long-suffering
phlegmatic
resigned
self-controlled
self-possessed
stoic
stolid
unflappable
exemplary
fatalistic
immovable
impassible
indomitable
mask-like
matter-of-fact
nonchalant
stony
uncomplaining
unfeeling
unflinching
unshaken
unsmiling
unyielding