Source : Webster's Revised Unabridged Dictionary (1913)

Intelligibly \In*tel"li*gi*bly\, adv.
   In an intelligible manner; so as to be understood; clearly;
   plainly; as, to write or speak intelligibly.

Source : WordNet®

intelligibly
     adv : in an intelligible manner; "the foreigner spoke to us quite
           intelligibly" [syn: {clearly}, {understandably}] [ant:
           {unintelligibly}]