1. Calm, peaceful, and untroubled; free from disturbance or agitation
The placid waters of the lake reflected the sunset.
As águas plácidas do lago refletiam o pôr do sol.
2. Characterized by tranquility; gentle and serene in nature
She had a placid demeanor that put everyone at ease.
Ela tinha uma natureza plácida que tranquilizava todos.