1 Definition
Pleasantly calm and undisturbed, whether describing a person's temperament, a body of water, or a quiet setting.
2 In Use
Even as the meeting grew heated, she stayed placid, sipping her tea and waiting for the noise to settle.
3 Word Origin
placere Lat. · to please → placidus Lat. · gentle, calm → placid 17th c. English
Placid grew out of the Latin verb for pleasing, and the logic is easy to feel: what pleases us tends to soothe us. Romans used placidus for people and things that were gentle, mild, and free of agitation, and the word kept that soft meaning when it arrived in English in the early 1600s. Over time it became a favorite for describing still water and even-tempered people alike.
💡Fun Fact
Placid has a surprisingly large family of cousins, all descended from the same Latin verb. To placate someone is to calm them down, to be complacent is to be a little too pleased with yourself, and a placebo is literally "I shall please" in Latin. Even the English word pleasure reaches back to the same root by way of Old French. Few word families trace such a neat line from delight to calm to a sugar pill.