tranquil tranquil /ˈtræŋkwɪl/

adjective

1. () (of a body of water) free from disturbance by heavy waves  ( smooth , unruffled , quiet , placid , still , tranquil )
   (of a body of water) free from disturbance by heavy waves
    A ribbon of sand between the angry sea and the placid bay
   a ribbon of sand between the angry sea and the placid bay
    The quiet waters of a lagoon
   the quiet waters of a lagoon
    A lake of tranquil blue water reflecting a tranquil blue sky
   a lake of tranquil blue water reflecting a tranquil blue sky
    A smooth channel crossing
   a smooth channel crossing
    Scarcely a ripple on the still water
   scarcely a ripple on the still water
    Unruffled water
   unruffled water
   
2. Not agitated; without losing self-possession  ( serene , tranquil , unagitated , calm )
   not agitated; without losing self-possession
    Spoke in a calm voice
   spoke in a calm voice
    Remained calm throughout the uproar
   remained calm throughout the uproar
    He remained serene in the midst of turbulence
   he remained serene in the midst of turbulence
    A serene expression on her face
   a serene expression on her face
    She became more tranquil
   she became more tranquil
    Tranquil life in the country
   tranquil life in the country