Definition of diagonal adjective from the Oxford Advanced Learner's Dictionary

diagonal

adjective
daɪˈæɡənl
 
; daɪˈæɡənl
 
 
(of a straight line) at an angle; joining two opposite sides of something at an anglediagonal stripesdiagonally
daɪˈæɡənəli
 
; daɪˈæɡənəli
 
adverbWalk diagonally across the field to the far corner and then turn left.