ETYMOLOGY
from Latin placidus (pleasing, favourable, gentle, mild, calm),
from root of placēre (to please)
EXAMPLE
“…There was never any thing more strange in the nature of Dogs, then that which happened at *Rhodes besieged by the Turk, for the Dogs did there discern betwixt Christians and Turks; for towards the Turks they were most eager, furious, and unappeaseable but towards Christians, although unknown, most easie, peaceable and placidious, which thing caused a certain Poet to write thus…”
From: The History of Four-footed Beasts, and Serpents
By Edward Topsell, 1607
Lexicophilia 