What does the word concave mean?

Usage examples for concave

  1. Beyond our atmosphere the sun would appear a rayless orb of fire in the midst of a black concave. – The Complete Poetical Works of Percy Bysshe Shelley Volume III by Percy Bysshe Shelley Edited by Thomas Hutchinson, M. A.
  2. The mouth of this granite half- circle was opened to the south, at least a quarter- mile in width; but on his left, a jutting spur almost at right angles to the main range, and some hundreds of yards closer to his position, shot across the space within the horseshoe bend, in such fashion that an observer, standing on the plain, would have half his view of the inner concave expanse shut off, except that part of the high north wall that towered above the spur. – Lahoma by John Breckinridge Ellis
  3. The spines are flat on the under- surface and concave on the upper, sharply pointed and broadest near the root. – Natural History of the Mammalia of India and Ceylon by Robert A. Sterndale