slantwise

slant +‎ -wise

slantwise (not comparable)

1. diagonal, in a direction or orientation between cardinal axes
   • 1858, John Greenleaf Whittier, "Telling the Bees" in The Works of John Greenleaf Whittier, Vol. I, Narrative and Legendary Poems,

     I can see it all now,—the slantwise rain / Of light through the leaves, / The sundown's blaze on her window-pane, / The bloom of her roses under the eaves.

slantwise (comparative more slantwise, superlative most slantwise)

1. diagonally, in a direction or orientation between cardinal axes
   • 1924, Herman Melville, Billy Budd, London: Constable & Co., Chapter 8,

     […] he had received a cut slantwise along one temple and cheek, leaving a long scar like a streak of dawn's light falling athwart the dark visage.

   • 1970, Larry Niven, Ringworld, page 113:

     Slantwise, a salamander-shaped sea came at them, growing.