The Collaborative International Dictionary of English v.0.48:

Empirically \Em*pir"ic*al*ly\, adv.
   By experiment or experience; without science; in the manner
   of quacks.
   [1913 Webster]

WordNet (r) 3.0 (2006):

empirically
    adv 1: in an empirical manner; "this can be empirically tested"
           [syn: empirically, through empirical observation, by
           trial and error] [ant: theoretically]