icebreaker
noun /ˈaɪsbreɪkə(r)/
  /ˈaɪsbreɪkər/
 - a strong ship designed to break a way through ice, for example in the Arctic or AntarcticTopics Transport by waterc2
 - a thing that you do or say, such as a game or a joke, to make people feel more relaxed, especially at the beginning of a meeting, party, etc.