Definition of "hollow"

Forests grew upon the barren hollows.

c. 1710–20, Matthew Prior, The First Hymn Of Callimachus: To Jupiter

This road leads through a sandy hollow shaded by trees for about a quarter of a mile, where it crosses the bridge famous in goblin story, and just beyond swells the green knoll on which stands the whitewashed church.

1820 March 5, Geoffrey Crayon [pseudonym; Washington Irving], “The Legend of Sleepy Hollow”, in The Sketch Book of Geoffrey Crayon, Gent., number VI, New York, N.Y.: […] C. S. Van Winkle, […], pages 110–111

I hate the dreadful hollow behind the little wood, / Its lips in the field above are dabbled with blood-red heath, / The red-ribb'd hedges drip with a silent horror of blood, / And Echo there, whatever is ask'd her, answers 'Death.'

1855, Alfred Tennyson, “Maud”, in Maud, and Other Poems, London: Edward Moxon, […], part I, stanza 1, page 1

Through thy battlements, Newstead, the hollow winds whistle:

1903, George Gordon Byron, On Leaving Newstead Abbey

To view with hollow eye and wrinkled brow

c. 1596–1598 (date written), William Shakespeare, “The Merchant of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, (please specify the act number in uppercase Roman numerals, and the scene number in lowercase Roman numerals)

[T]he Converſation (if it may be called ſo) was ſeldom ſuch as could entertain a Lady. It conſiſted chiefly of Hollowing, Singing, Relations of ſporting Adventures, B—d—y, and Abuſe of Women and of the Government.

1749, Henry Fielding, chapter IV, in The History of Tom Jones, a Foundling, volume III, London: A[ndrew] Millar, […], book VII, page 26

He has hollowed the hounds.

1814 July 7, [Walter Scott], Waverley; […], volumes (please specify |volume=I to III), Edinburgh: […] James Ballantyne and Co. for Archibald Constable and Co.; London: Longman, Hurst, Rees, Orme, and Brown