n. 1. (genetics) the interchange of sections between pairing homologous chromosomes during the prophase of meiosis. Syn. -- crossing over. [ WordNet 1.5 ]
2. a structure, such as a bridge, bearing a path for crossing over a river or highway. [ PJC ]
3. votes from members of one political party cast for candidates of another party; -- called also crossover vote; as, there was a high crossover in this election. [ PJC ]
4. a member of one political party who votes for a candidate of another party; -- called also crossover voter. [ PJC ]
5. (Plumbing) a U-shaped section of pipe which serves to pass one pipeline over another which is directly in its path. [ PJC ]