Source : Webster's Revised Unabridged Dictionary (1913)

Shortage \Short"age\, n.
   Amount or extent of deficiency, as determined by some
   requirement or standard; as, a shortage in money accounts.

Source : WordNet®

shortage
     n 1: the property of being an amount by which something is less
          than expected or required [syn: {deficit}, {shortfall}]
     2: an acute insufficiency [syn: {dearth}, {famine}]