Definition of "opacous"

The firm opacous Globe / Of this round World, whose first convex divides / The luminous inferior Orbs.

1667, John Milton, “(please specify the book number)”, in Paradise Lost. […], London: […] [Samuel Simmons], […]; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873,

And vve particularly remember, that, being at ſome diſtance from London one Night, that the People, upon a very vvell-come Occaſion, teſtified their Joy by numerous Bon-fires; though, by reaſon of the Interpoſition of the Houſes, vve could not ſee the Fires themſelves, yet vve could plainly ſee the Air all enlighten'd over and near the City; vvhich argu'd, that the lucid Beams ſhot upvvards from the Fires, met in the Air with the Corpuſcles opacous enough to reflect them to our Eyes.

1659 December 30 (date written), Robert Boyle, “[Experiment 37]”, in New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects, (Made, for the Most Part, in a New Pneumatical Engine) […], Oxford, Oxfordshire: […] H[enry] Hall, printer to the University, for Tho[mas] Robinson, published 1660, page 309

[I]f you take ammel that is almost opacous, and grind it very well on a Porphyry, or Serpentine, the small particles will by reason of their flaws, appear perfectly opacous […]

1665, R[obert] Hooke, chapter X, in Micrographia: Or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses. With Observations and Inquiries thereupon, London: Printed by Jo[hn] Martyn, and Ja[mes] Allestry, printers to the Royal Society, […]

The upper wings are opacous; at their hinder ends, where they lap over, transparent, like the wing of a fly.

1681, Nehemiah Grew, Musæum Regalis Societatis. Or A Catalogue & Description of the Natural and Artificial Rarities Belonging to the Royal Society and Preserved at Gresham Colledge. […], London: […] W. Rawlins, for the author