NOUN (3)

1. a bifurcating branch (one or both of them);

2. the place where something divides into two branches;

3. the act of splitting into two branches;

The Collaborative International Dictionary of English v.0.48:

Bifurcation \Bi`fur*ca"tion\, n. [Cf. F. bifurcation.]
   A forking, or division into two branches.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bifurcation
    n 1: a bifurcating branch (one or both of them)
    2: the place where something divides into two branches
    3: the act of splitting into two branches