The Collaborative International Dictionary of English v.0.48:

Abaxial \Ab*ax"i*al\ ([a^]b*[a^]ks"[i^]*al), Abaxile \Ab*ax"ile\
   ([a^]b*[a^]ks"[i^]l), a. [L. ab + axis axle.] (Bot.)
   Away from the axis or central line; eccentric. --Balfour.
   [1913 Webster]

WordNet (r) 3.0 (2006):

abaxial
    adj 1: facing away from the axis of an organ or organism; "the
           abaxial surface of a leaf is the underside or side facing
           away from the stem" [syn: abaxial, dorsal] [ant:
           adaxial, ventral]