phlegmatic
adjective
[ flɛɡˈmatɪk ]
• (of a person) having an unemotional and stolidly calm disposition.
• "the phlegmatic British character"
Similar:
self-controlled,
calm,
cool,
composed,
and collected,
cool-headed,
controlled,
serene,
tranquil,
placid,
impassive,
self-possessed,
self-confident,
self-assured,
stolid,
imperturbable,
unruffled,
poised,
level-headed,
dispassionate,
philosophical,
unflappable,
equanimous,
Origin:
Middle English (in the sense ‘relating to the humour phlegm’): from Old French fleumatique, via Latin from Greek phlegmatikos, from phlegma ‘inflammation’ (see phlegm).