The Collaborative International Dictionary of English v.0.48:

Breakup \Break"up`\, Break-up \Break"-up`\, n.
   Disruption; coming apart; a separation and dispersion of the
   parts or members; as, a break-up of a meeting, assembly, or
   dinner party; the break-up of a spacecraft on re-entry into
   the atmosphere.

   Syn: separation, detachment.
        [1913 Webster +PJC]

   2. the termination of a relationship; a break-up of the
      government; the break-up of a marriage; the break-up of a
      business partnership; the break-up of a comedy team.

   Syn: dissolution.
        [WordNet 1.5 +PJC]