Source : Webster's Revised Unabridged Dictionary (1913)

Adynamic \Ad`y*nam"ic\, a. [Cf. F. adynamique. See {Adynamy}.]
   1. (Med.) Pertaining to, or characterized by, debility of the
      vital powers; weak.

   2. (Physics) Characterized by the absence of power or force.

   {Adynamic fevers}, malignant or putrid fevers attended with
      great muscular debility.

Source : WordNet®

adynamic
     adj 1: characterized by an absence of force or forcefulness [syn: {undynamic}]
            [ant: {dynamic}]
     2: lacking strength or vigor [syn: {asthenic}, {debilitated}, {enervated}]