Emily Dickinson Lexicon

PLAC'ID, a. [L. placidus, from placo, to appease.]

1. Gentle; quiet; undisturbed; equable; as, a placid motion of the spirits. – Bacon.
2. Serene; mild; unruffled; indicating peace of mind; as, a placid countenance or smile.
3. Calm; tranquil; serene; not stormy; as, a placid sky.
4. Calm; quiet; unruffled; as, a placid stream.