Source : Webster's Revised Unabridged Dictionary (1913)

Sustenance \Sus"te*nance\, n. [OF. sustenance, sostenance,
   soustenance: cf. L. sustenentia endurance. See {Sustain}.]
   1. The act of sustaining; support; maintenance; subsistence;
      as, the sustenance of the body; the sustenance of life.

   2. That which supports life; food; victuals; provisions;
      means of living; as, the city has ample sustenance. ``A
      man of little sustenance.'' --Chaucer.

            For lying is thy sustenance, thy food. --Milton.

Source : WordNet®

sustenance
     n 1: a source of materials to nourish the body [syn: {nutriment},
           {nourishment}, {nutrition}, {aliment}, {alimentation},
          {victuals}]
     2: the financial means whereby one lives; "each child was
        expected to pay for their keep"; "he applied to the state
        for support"; "he could no longer earn his own livelihood"
        [syn: {support}, {keep}, {livelihood}, {living}, {bread
        and butter}]
     3: the act of sustaining life by food or providing a means of
        subsistence; "they were in want of sustenance"; "fishing
        was their main sustainment" [syn: {sustentation}, {sustainment},
         {maintenance}, {upkeep}]