Definition of "slantwise"

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.

1858, John Greenleaf Whittier, "Telling the Bees" in The Works of John Greenleaf Whittier, Vol. I, Narrative and Legendary Poems

[…] 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.

1924, Herman Melville, chapter 8, in Billy Budd‎, London: Constable & Co.

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

1970, Larry Niven, Ringworld, page 113