Source : Webster's Revised Unabridged Dictionary (1913)

Slumberous \Slum"ber*ous\, a.
   1. Inviting slumber; soporiferous. ``Pensive in the
      slumberous shade.'' --Pope.

   2. Being in the repose of slumber; sleepy; drowsy.

            His quiet and almost slumberous countenance.
                                                  --Hawthorne.

Source : WordNet®

slumberous
     adj 1: quiet and tranquil; "a slumberous June morning" [syn: {slumbrous}]
     2: inclined to or marked by drowsiness; "slumberous (or
        slumbrous) eyes"; "`slumbery' is archaic"; "the sound had
        a a somnolent effect" [syn: {slumbery}, {slumbrous}, {somnolent}]