Source : Webster's Revised Unabridged Dictionary (1913)

Euphemistic \Eu`phe*mis"tic\, Euphemistical \Eu`phe*mis"tic*al\,
   a.
   Pertaining to euphemism; containing a euphemism; softened in
   expression. -- {Eu`phe*mis"tic*al*ly}, adv.

Source : WordNet®

euphemistically
     adv : in a euphemistic manner; "his violent death was
           euphemistically referred to as a passing away"