From WordNet (r) 3.0 (2006) :
rearwards
adv 1: at or to or toward the back or rear; "he moved back";
"tripped when he stepped backward"; "she looked rearward
out the window of the car" [syn: back, backward,
backwards, rearward, rearwards] [ant: forrad,
forrard, forward, forwards, frontward,
frontwards]