Why do Catholics refer to the container of the Host as a pyx?

As per Wikipedia:

"A pyx or pix (Latin: pyxis, transliteration of Greek: ?????, box-wood receptacle, from ?????, box-tree) is a small round container used in the Catholic, Old Catholic and Anglican Churches to carry the consecrated host (Eucharist), to the sick or invalid or those otherwise unable to come to a church in order to receive Holy Communion. The term can also be used in Archaeology and art history to describe small round lidded boxes designed for any purpose from antiquity or the Middle Ages, such as those used to hold coins for the Trial of the Pyx in England."