Wordnet 3.0
ADVERB (1)
1. 
 in an invincible manner; 
- Example: "invincibly, the troops moved forward"
The Collaborative International Dictionary of English v.0.48:
Invincible \In*vin"ci*ble\, a. [L. invincibilis: cf. F.
   invincible. See In- not, and Vincible.]
   Incapable of being conquered, overcome, or subdued;
   unconquerable; insuperable; as, an invincible army, or
   obstacle.
   [1913 Webster]
         Lead forth to battle these my sons
         Invincible.                              --Milton.
   -- In*vin"ci*ble*ness, n. -- In*vin"ci*bly, adv.
   [1913 Webster]
WordNet (r) 3.0 (2006):
invincibly
    adv 1: in an invincible manner; "invincibly, the troops moved
           forward"