unperturbed (adj.)

• calm
• cloistered
• cool
• dwindling
• halcyon
• hushed
• impassive
• isolated
• moldering
• pacific
• peaceable
• peaceful
• placid
• quiescent
• quiet
• reposeful
• restful
• resting
• secluded
• sequestered
• sheltered
• smooth
• still
• stilly
• stoic
• stolid
• tranquil
• unagitated
• undisturbed
• unexcited
• unflustered
• unimpassioned
• unmoved
• unruffled
• unstirred
• untroubled
• unworried
• waning