imperturbable
adj.
definition
unexcitable; unflustered; calm
synonyms
composed
cool
nerveless
antonyms
excitable
jittery
perturbable
sentences
1.) The students were imperturbable and refused to laugh at their teacher's corny jokes.
2.) The worst kind of people to prank are the ones that act imperturbable.
Funny guy makes Royal Guard Laugh at Buckingham Palace