calm
take a breath
encalm
keep one's pants on
salve
keep one's hair on
placify
quiet
still
lull
calm down
tranquilize
tranquillise
tranquillize
quieten
get ahold of oneself
chillax
relax
slow one's roll
unruffle
keep one's shirt on
keep one's knickers on
compose
calm your farm
sile
lay chilly
subside
calmen
sort oneself out
smooth
defreak
allay
have one's wits about one
pour oil on troubled waters
keep one's head
hose down
settle
peacen
bestill
clear up
soothe
untranquilize
keep a cool head
cool it
conciliate
chill out
simmer down
settle down
cool off
hold one's nerve