The Collaborative International Dictionary of English v.0.48:

Amiably \A"mi*a*bly\, adv.
   In an amiable manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

amiably
    adv 1: in an affable manner; "`Come and visit me,' he said
           amiably" [syn: affably, amiably, genially]