Source : Webster's Revised Unabridged Dictionary (1913)

Experimentally \Ex*per`i*men"tal*ly\, adv.
   By experiment; by experience or trial. --J. S. Mill.

Source : WordNet®

experimentally
     adv : in an experimental fashion; "this can be experimentally
           determined" [syn: {by experimentation}, {through an
           experiment}]