A bifurcation (from latin bifurcare) can be

• river bifurcation - the (infrequently observed) forking of a river into distributaries
• a period-doubling phenomenon known from chaos theory, see: bifurcation diagram
• the partial or total splitting of a human penis for pleasurable or decorative reasons.
• the partial or total splitting of a human tongue for pleasurable or decorative reasons.

See also: fork