placid
/ˈplæsɪd/adjective
1- (of a person or animal) not easily upset or excited（人, 动物）平和的, 温和的：
this horse has a placid nature.
这匹马性情温和。
1.1
- (especially of a place or stretch of water) calm and peaceful, with little movement or activity（尤指地方或水域）平静的, 宁静的：
the placid waters of a small lake.
小湖平静的水面。
派生词
placidity
nounplacidly
adverb词源
early 17th cent.: from French placide, from Latin placidus, from placere 'to please'.