Definition of icebreakers:
(n) :
(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.
(n) :
(nautical) A ship designed to break through ice so that it, or other ships coming behind, can navigate on frozen seas.
(n) :
(theater) A lively song and dance routine at the start of a musical.