The Collaborative International Dictionary of English v.0.48:
Agonizingly \Ag"o*ni`zing*ly\, adv. With extreme anguish or desperate struggles. [1913 Webster]WordNet (r) 3.0 (2006):
agonizingly adv 1: in a very painful manner; "the progress was agonizingly slow" [syn: agonizingly, excruciatingly, torturously]