The hackle is a clipped plume or short spray of coloured feathers that is attached to a military headdress, with different colours being associated with particular regiments.
In the British Army and the armies of some Commonwealth countries, the hackle is worn by some infantry regiments, especially those designated as fusilier regiments and those with Scottish and Northern Irish origins.
A shako (/ˈʃækoʊ/, /ˈʃeɪkoʊ/, or /ˈʃɑːkoʊ/) is a tall, cylindrical military cap, usually with a visor, and sometimes tapered at the top. It is usually adorned with an ornamental plate or badge on the front, metallic or otherwise; and often has a feather, hackle, or pompom attached at the top.
Extensively used as an item of military headgear during the nineteenth and early twentieth centuries, the shako now survives as part of some ceremonial uniforms.
A plume is a special type of bird feather, possessed by egrets, ostriches, birds of paradise, quetzals, pheasants, peacocks and quails. They often have a decorative or ornamental purpose, commonly used among marching bands and the military, worn on the hat or helmet of the wearer. When used on military headdresses, the clipped feather plume is referred to as the hackle.