fob
noun [ C ] uk/fɒb/ us/fɑːb/
钥匙链;（尤指旧时的）怀表短链
a piece of leather or other material to which a group of keys is fastened, or a chain or piece of material used, especially in the past, to fasten a watch to a man's waistcoat
a key fob 钥匙链
a fob watch 带表链的怀表