icebreaker

1. (nautical) A ship designed to break through ice so that it, or other ships coming behind, can navigate on frozen seas.Examples: "The steel hulls of ice-breakers are much thicker than those of standard vessels."; "My father's Bonneville was cutting its way toward us like an icebreaker moving through my whole state of consciousness."

2. (figurative) A game, activity, humorous anecdote, etc., designed to ease tension and encourage interaction among individuals in a situation where they do not know each other well.Examples: "The new college hallmates were awkward with each other at first, but after a game of charades as an icebreaker, they were laughing like old friends."; "The key purpose of an icebreaker is to introduce your group members to each other and to introduce your training session topic. A well-planned icebreaker ensures that a training session will start with more involvement and focus."figuratively

3. (theater) A lively song and dance routine at the start of a musical.Examples: "At the moment the curtain went up there had to be a lively ensemble number of principals and chorus singing and dancing, the traditional “icebreaker” that also covered up the noise of late-arriving ticket holders getting to their seats."