1 : marked by a state of tranquil repose; "the quiescent melancholy of the town"
2 : (of a body of water) free from disturbance by heavy waves; "a ribbon of sand between the angry sea and the placid bay"; "the quiet waters of a lagoon"; "a lake of tranquil blue water reflecting a tranquil blue sky"; "a smooth channel crossing"; "scarcely a ripple on the still water"; "unruffled water"
adjectif
1 : characterized by an absence or near absence of agitation or activity
2 : of the sun characterized by a low level of surface phenomena like sunspots e.g.