Wordnet 3.0
ADVERB (1)
1. 
 in a peacefully serene manner; 
- Example: "I had the feeling that he was waiting, too--serenely patient"
The Collaborative International Dictionary of English v.0.48:
Serenely \Se*rene"ly\, adv.
   1. In a serene manner; clearly.
      [1913 Webster]
            Now setting Ph[oe]bus shone serenely bright. --Pope.
      [1913 Webster]
   2. With unruffled temper; coolly; calmly. --Prior.
      [1913 Webster]
WordNet (r) 3.0 (2006):
serenely
    adv 1: in a peacefully serene manner; "I had the feeling that he
           was waiting, too--serenely patient"