Definition of "purpureal"

[G]liding thro' his daughter's honour'd ſhades, / The ſmooth Penéus from his glaſſy flood / Reflects purpureal Tempe's pleaſant ſcene?

1744, [Mark Akenside], “Book the First”, in The Pleasures of Imagination. A Poem. In Three Books, London: […] R[obert] Dodsley […], page 16, lines 296–298

[T]he fair star / That gems the glittering coronet of morn, / Sheds not a light so mild, so powerful, / As that which, bursting from the Fairy's form, / Spread a purpureal halo round the scene, / Yet with an undulating motion, / Swayed to her outline gracefully.

1813, Percy Bysshe Shelley, “Canto I”, in Queen Mab; […], London: […] P. B. Shelley, […], page 6

Of all that is most beauteous—imaged there / In happier beauty; more pellucid streams, / An ampler ether, a diviner air, / And fields invested with purpureal gleams; [...]

1815, William Wordsworth, “Laodamia”, in Poems […], volume I, London: […] Longman, Hurst, Rees, Orme, and Brown, […], page 229

But not ere him who summoneth / I first have seen, enwound / With glooming robes purpureal, cypress-crowned; [...]

1893, Francis Thompson, “The Hound of Heaven”, in The Works of Francis Thompson, volume I (Poems), New York, N.Y.: Charles Scribner’s Sons […], published 1913, page 112

Above the altar-lace / he mounted a triptych of the Assumption / with coarse, purpureal clouds, a prescient Madonna / drawn from Leonardo's "Our Lady of the Rocks."

1973, Derek Walcott, “[Homage to Gregorias] Chapter 10”, in Another Life, New York, N.Y.: Farrar, Straus and Giroux, page 63