Source : Webster's Revised Unabridged Dictionary (1913)

Damnably \Dam"na*bly\, adv.
   1. In a manner to incur severe censure, condemnation, or
      punishment.

   2. Odiously; detestably; excessively. [Low]

Source : WordNet®

damnably
     adv : in a damnable manner; "kindly Arthur--so damnably , politely
           , endlessly persistent!" [syn: {damned}, {cursedly}]