Sedate
/sɪˈdeɪt/
verb
To calm or put (a person) to sleep using a sedative drug.
To make tranquil.
Synonyms: calm, soothe, tranquilize, tranquilize
adjective
(of a person or their behaviour) Remaining composed and dignified, and avoiding too much activity or excitement.
(of an object, particularly a building) Not overly ornate or showy.