The Collaborative International Dictionary of English v.0.48:

Nappy \Nap"py\, n.; pl. Nappies. [OE. nap, AS. hnaep cup,
   bowl. See Hanaper.]
   A round earthen dish, with a flat bottom and sloping sides.
   [Written also nappie.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

nappy \nap"py\, n.; pl. nappies.
   A diaper[4]. [Chiefly Brit.]
   [PJC]