'icebreaker' definitions:

Definition of 'icebreaker'

From: WordNet
noun
A ship with a reinforced bow to break up ice and keep channels open for navigation [syn: icebreaker, iceboat]
noun
A beginning that relaxes a tense or formal atmosphere; "he told jokes as an icebreaker"

Definition of 'icebreaker'

From: GCIDE
  • icebreaker \icebreaker\ n.
  • 1. a ship with a reinforced bow and powerful engines designed to break up layers of ice on waterways and keep channels open for navigation.
  • Syn: iceboat. [WordNet 1.5]
  • 2. A remark or action intended to relieve tension or reduce formality when initiating conversation or beginning a speech; it is often a humorous or light remark. [PJC]