The boy was remarkably unperturbed by the terrible news.
Composed, undisturbed, unruffled, or placid. Those words mean unperturbed.
Calm, unruffled, serene
The sentence, Janet thought Sean's answer was very reassuring, is an example of how to use reassuring in a sentence.
Apple trees are deciduous.
Thankfully, we are all unhurt.
unperturbed
The nasty argument left her unperturbed. (She was not bothered)
He doesn't seem unperturbed by the comment Eric made.
Despite the chaos around her, she remained unperturbed and continued to focus on her work.
unfazed
That is the correct spelling of the word "unperturbed" (unaffected, calm).
Composed, undisturbed, unruffled, or placid. Those words mean unperturbed.
calmtranquilplacidundisturbedunstirredcollectedserene
Undisturbed, calm and collected
Calm, unruffled, serene
Not to disturb someone or something
びくともし