pacifier

noun
  1. An object, typically made of rubber or plastic, designed for a baby to suck on, which helps soothe and calm them. noun
    The baby stopped crying as soon as she was given her pacifier.
    Parents often use a pacifier to help their infants fall asleep.
  2. A person or thing that pacifies or calms someone or something. noun
    The mediator acted as a pacifier during the heated negotiations.
    Music can be a great pacifier for people feeling stressed.