1. The distribution of the outstanding cards in a suit between the unseen hands, for example ‘trumps might break 4-1’. Also used colloquially to describe a favourable break (e.g. 3-3), or a nearly even break when an odd number of cards is missing (e.g. 3-2). For example: ‘If the clubs break…’
2. To defeat (set) a contract.
3. To break a new suit is to open it up, i.e. make the first lead of the suit.