shak·o also shack·o (shāk'ō, shā'kō, shä'-) n.
pl.shak·os also shack·os or shak·oes also shack·oes A stiff, cylindrical military dress hat with a metal plate in front, a short visor, and a plume.
[French schako, from Hungarian csákó, from csákós (süveg), pointed (cap), from csák, peak, perhaps from Middle High German zacke, tack, nail.]