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Webster 1913 Edition

Adj.

[L.

placidus

, originally, pleasing, mild, from

placere

to please: cf. F.

placide

. See

Pleased; contented; unruffied; undisturbed; serene; peaceful; tranquil; quiet; gentle.

“That placid aspect and meek regard.”

Milton.

“Sleeping . . . the placid sleep of infancy.”

Macaulay.

Adj.

[L. placidus, from placo, to appease.]

Gentle; quiet; undisturbed; equable; as a placid motion of the spirits.

Serene; mild; unruffled; indicating peace of mind; as a placid countenance or smile.

Calm; tranquil; serene; not stormy; as a placid sky.

Calm; quiet; unruffled; as a placid stream.

See also: placid

plàcid m ‎(feminine plàcida, masculine plural plàcids, feminine plural plàcides)

serene; calm
- 2004, Carme Meix, Cercles, ISBN 8497910222, page 76:
  Era un vespre plàcid
  it was a calm evening