Wordnet 3.0
ADVERB (2)
1. 
 in a stable solid fixed manner; 
- Example: "the boulder was balanced stably at the edge of the canyon"2. 
 in a stable unchanging manner; 
- Example: "the death rate in Russia has been stably high"
The Collaborative International Dictionary of English v.0.48:
Stably \Sta"bly\ (st[=a]"bl[y^]), adv.
   In a stable manner; firmly; fixedly; steadily; as, a
   government stably settled.
   [1913 Webster]
WordNet (r) 3.0 (2006):
stably
    adv 1: in a stable solid fixed manner; "the boulder was balanced
           stably at the edge of the canyon"
    2: in a stable unchanging manner; "the death rate in Russia has
       been stably high"