placid (adj.)

• bane
• calm
• cloistered
• collected
• composed
• cool
• coolheaded
• detached
• dwindling
• easy
• easygoing
• epidemic
• halcyon
• hushed
• impassive
• irenic
• isolated
• moldering
• pacific
• peaceable
• peaceful
• philosophical
• poised
• quiescent
• quiet
• rash
• reposeful
• restful
• resting
• secluded
• self-possessed
• sequestered
• serene
• sheltered
• smooth
• still
• stilly
• stoic
• stolid
• tranquil
• unagitated
• undisturbed
• unmoved
• unperturbed
• unruffled
• untroubled
• waning