The Collaborative International Dictionary of English v.0.48:
Astraddle \A*strad"dle\, adv. [Pref. a- + straddle.] In a straddling position; astride; bestriding; as, to sit astraddle a horse. [1913 Webster]WordNet (r) 3.0 (2006):
astraddle adv 1: with one leg on each side; "she sat astride the chair" [syn: astride, astraddle]