Source : Webster's Revised Unabridged Dictionary (1913)

Priggish \Prig"gish\, a.
   Like a prig; conceited; pragmatical. -- {Prig"gish*ly}, adv.
   -- {Prig"gish-ness}, n.

Source : WordNet®

priggishly
     adv : in a priggish manner; "this professor acts so
           priggishly--like a moderator with a gavel!"