calmar
transitive verb
1 (relajar) [+persona] to calm (down); [+ánimos] to calm; [+nervios] to calm; steady
intenté calmarla pero seguía llorando I tried to calm her down but she kept crying; estas pastillas le ayudarán a calmar la ansiedad these pills will help reduce o relieve your anxiety
esta medida calmará la tensión en el país this measure will reduce tension in the country