(n) the act of sustaining life by food or providing a means of subsistence, Syn. sustainment, maintenance, upkeep, sustentation, Example:they were in want of sustenance; fishing was their main sustainment
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
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. [ 1913 Webster ]
2. That which supports life; food; victuals; provisions; means of living; as, the city has ample sustenance. “A man of little sustenance.” Chaucer. [ 1913 Webster ]
For lying is thy sustenance, thy food. Milton. [ 1913 Webster ]