A cloak of a kind originally worn in South America with a hole in the middle to put the head through (6)

(Other definitions for poncho that I've seen before include "South American cloak with slit for the head" , "Blanket-like garment" , "Kind of blanket with hole for head" , "Overgarment with hole for head" , "Blanket-like cloak with slit for head" .)