Puppis

"stern or aftermost deck of a ship," c. 1400, from Old French poupe "stern of a ship" (14c.), from Old Provençal or Italian poppa, from Latin puppis "poop, stern," a word of uncertain origin. Also "a deck above the ordinary deck on the aftermost part of a ship." As a verb, "to break heavily over the stern of a ship" (of waves, etc.). Poop deck is attested by 1779.