placid vs tranquil

placid and tranquil both are adjectives.

Word	Noun	Adjective	Verb	Adverb
placid	No	Yes	No	No
tranquil	No	Yes	No	No

As adjectives, placid and tranquil are synonyms defined as:

placid and tranquil: (of a body of water) free from disturbance by heavy waves

Other synonyms of placid include quiet, smooth, still, unruffled.

placid (adjective)	tranquil (adjective)
(of a body of water) free from disturbance by heavy waves	(of a body of water) free from disturbance by heavy waves
not easily irritated	not agitated; without losing self-possession