In the context of a windless period it can be "Kalme", "Flaute", "Stille" or "Windstille".
In the context of staying calm it can be "Gelassenheit", "gefasst", "gelassen", "ruhig" or "seelenruhig"
Beruhigen
You can say "calm down" in different ways such as "take a deep breath," "relax," or "stay calm."
In Hawaiian, you would say "hoʻomaluhia".
You can transfer it with "Bleib ruhig und mach weiter". It should be really close to your term.
"Calm" in Hawaiian is "maluhia."
To calm a Rottweiler you must (if it is trained) say go to your bed and then say lie down if he or se does not comply then ignore he or she and he or she will calm down.
In Sanskrit, "be calm" can be translated as "शांत रहो" (śānt raho).
The Sea of Galilee
Calm Down is when someone mad or something so people usually say "calm down"
Calme.
평온
Very calm is "très calme" in French