Source : Webster's Revised Unabridged Dictionary (1913)

Allhallow \All`hal"low\, Allhallows \All`hal"lows\, n.
   1. All the saints (in heaven). [Obs.]

   2. All Saints' Day, November 1st. [Archaic]

Source : WordNet®

Allhallows
     n : a Christian feast day honoring all the saints; first
         observed in 835 [syn: {All Saints' Day}, {November 1}, {Hallowmas},
          {Hallowmass}]