From The Collaborative International Dictionary of English v.0.48 :
Staidly \Staid"ly\, adv. In a staid manner, sedately. [1913 Webster]From WordNet (r) 3.0 (2006) :
staidly adv 1: in a grave and sober manner; "he walked soberly toward the altar" [syn: gravely, soberly, staidly]