security blanket
noun [ C ] uk/sɪˈkjʊə.rɪ.ti ˌblæŋ.kɪt/ us/sɪˈkjʊr.ə.t̬i ˌblæŋ.kɪt/
安乐毯;给婴儿（或幼儿）安全感之物
a soft object such as a small piece of cloth or a toy that is very familiar to a baby or young child and makes him or her feel safe
安全保障
something that makes you feel safe or confident