unperturbed
1. [ adjective ] free from emotional agitation or nervous tension
Synonyms: unflustered unruffled unflurried
Examples:

"the waiters were unflurried and good natured" "with contented mind and unruffled spirit"- Anthony Trollope

Related terms: composed
Similar spelling:   unpermed
  unperformed
  unperceived
  unperplexed
  unpierced
  unpersuaded
  unperson
  unperceptive
  unperceiving
  unperceivable
  uniparous