Source : Webster's Revised Unabridged Dictionary (1913)

Diagnose \Di`ag*nose"\, v. t. & i.
   To ascertain by diagnosis; to diagnosticate. See
   {Diagnosticate}.

Source : WordNet®

diagnose
     v 1: determine or distinguish the nature of a problem or an
          illness through a diagnostic analysis [syn: {name}]
     2: subject to a medical analysis