Motivated by existing and recent data on possible neutrino oscillation
s, we propose a model of four light neutrinos (nu(e), nu(mu), nu(tau),
and a singlet nu(S)) with a pattern of masses and mixing derivable fr
om a discrete Z(5) symmetry and the seesaw mechanism. Atmospheric neut
rino oscillations occur between nu(mu) and nu(tau) as pseudo Dirac par
tners, whereas solar neutrino oscillations occur between nu(e) and nu(
mu) to be account for the recent observation of the LSND (Liquid Scint
illator Neutrino Detector) experiment.