The Collaborative International Dictionary of English v.0.48:

Rapidly \Rap"id*ly\ (r[a^]p"[i^]d*l[y^]), adv.
   In a rapid manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rapidly
    adv 1: with rapid movements; "he works quickly" [syn: quickly,
           rapidly, speedily, chop-chop, apace] [ant:
           easy, slow, slowly, tardily]