Synapomorphy

From Freepedia

Shared characteristics that define a cladistic grouping. An apomorphy (derived or specialised character) shared by two or more groups which originated in their last common ancestor (from the Greek words apo = from and morphy = shape). Synapomorphy

A character shared by two or more taxa which was derived from their common ancestor. In cladistics, synapomorphies are used to establish phylogenies.