What is "tropaion"

A tropaion (, ), whence English " trophy" is derived, is an ancient Greek and later Roman monument set up to commemorate a victory over one's foes. Typically this takes the shape of a tree, sometimes with a pair of arm-like branches (or, in later times, a pair of stakes set crosswise) upon which is hung the armour of a defeated and dead foe. The tropaion is then dedicated to a god in thanksgiving for the victory.