cool as a cucumber
imperturbability
coolness
imperturbableness
compose
calm
keep one's pants on
calmness
have one's wits about one
still
equanimous
tranquilize
tranquillise
quieten
lull
quiet
calm down
tranquillize
cucumber
calmen
countenance
self-possession
keep one's knickers on
reposed
sile
settle
tranquillizingly
keep one's hair on
cool
lown
unfrenzied
calmative
salve
keep one's head
centered
bestill
pour oil on troubled waters
hold one's nerve
unpanicked
peacen
placid
chill
unfrazzled
composure
calmish
halcyon
complacently
heropanti
encalm
coolheaded