ETYM Latin placidus, originally, pleasing, mild, from placere to please: cf. French placide. Related to Please.
1. Free from disturbance; SYN. quiet, still, tranquil, unruffled.
2. Without untoward incident or disruption; SYN. quiet.
ETYM Latin serenus to grow dry.
1. Calm and peaceful.
2. Completely clear and fine.
ETYM Latin tranquillus; probably from trans across, over + a word akin to quietus quiet: cf. French tranquille. Related to Quiet.
Quiet; calm; undisturbed; peaceful; not agitated.