placid

Etymology

From French placide, from Latin placidus (“peaceful, calm, placid”), from placeō (“please, satisfy”).

adj

1. calm and quiet; peaceful; tranquil
   a placid disposition
   a placid lake
   April advanced to May: a bright serene May it was; days of blue sky, placid sunshine, and soft western or southern gales filled up its duration. 1847, Charlotte Brontë, chapter 9, in Jane Eyre, HTML edition
   The ant has made himself illustrious / Through constant industry industrious. / So what? / Would you be calm and placid / If you were full of formic acid? 1941, Ogden Nash, “The Ant”, in The Face is Familiar, Garden City Publishing Company, page 224
   [I]n the 575 days since [Oscar] Pistorius shot dead his girlfriend Reeva Steenkamp, there has been an unseemly scramble to construct revisionist histories, to identify evidence beneath that placid exterior of a pugnacious, hair-trigger personality. 21 October 2014, Oliver Brown, “Oscar Pistorius jailed for five years – sport afforded no protection against his tragic fallibilities: Bladerunner's punishment for killing Reeva Steenkamp is but a frippery when set against the burden that her bereft parents, June and Barry, must carry [print version: No room for sentimentality in this tragedy, 13 September 2014, p. S22]”, in The Daily Telegraph (Sport)