The Collaborative International Dictionary of English v.0.48:

Napkin \Nap"kin\, n. [Dim. of OF. nape a tablecloth, cloth, F.
   nappe, L. mappa. See Napery.]
   1. A little towel, made of cloth or paper, esp. one for
      wiping the fingers and mouth at table.
      [1913 Webster]

   2. A handkerchief. [Obs.] --Shak.
      [1913 Webster]

   Napkin pattern. See Linen scroll, under Linen. --
      Napkin ring, a ring of metal, ivory, or other material,
      used to inclose a table napkin.

   paper napkin, a napkin made of paper, intended to be
      disposed of after use.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

napkin
    n 1: a small piece of table linen that is used to wipe the mouth
         and to cover the lap in order to protect clothing [syn:
         napkin, table napkin, serviette]
    2: garment consisting of a folded cloth drawn up between the
       legs and fastened at the waist; worn by infants to catch
       excrement [syn: diaper, nappy, napkin]