Definition of "tor"

Bursdon and Welsford were then, as now, a rolling range of dreary moors, unbroken by tor or tree, […]

1855, Charles Kingsley, Westward Ho!: Or, The Voyages and Adventures of Sir Amyas Leigh, Knight, […], volume I, Cambridge, Cambridgeshire: Macmillan & Co., page 183

The moon was low upon the right, and the jagged pinnacle of a granite tor stood up against the lower curve of its silver disc.

1901 August – 1902 April, A[rthur] Conan Doyle, chapter 9, in The Hound of the Baskervilles: Another Adventure of Sherlock Holmes, London: George Newnes, […], published 1902

She had slipped the letters into her pocket next to the packet of antique documents and had taken an umbrella—as the sky was ominous out over the distant tors—and strolled around the manor house and down the road toward the village.

2008, Lydia Joyce, Shadows of the Night‎, Signet Eclipse, page 242