Source : Webster's Revised Unabridged Dictionary (1913)

Undermanned \Un`der*manned"\, a. (Naut.)
   Insufficiently furnished with men; short-handed.

Source : WordNet®

undermanned
     adj : inadequate in number of workers or assistants etc.; "they're
           rather short-handed at the moment"; "overcrowded and
           understaffed hospitals" [syn: {short-handed}, {short-staffed},
            {understaffed}]