Search Result for "regretfully": 
Wordnet 3.0

ADVERB (1)

1. with regret (used in polite formulas);
- Example: "I must regretfully decline your kind invitation"



The Collaborative International Dictionary of English v.0.48:

Regretful \Re*gret"ful\ (-f?l), a.
   Full of regret; indulging in regrets; repining. --
   Re*gret"ful*ly, adv.
   [1913 Webster] re-group


WordNet (r) 3.0 (2006):

regretfully
    adv 1: with regret (used in polite formulas); "I must
           regretfully decline your kind invitation"