Definition of "surf"

[…] perhaps it was the look of the island, with its gray, melancholy woods, and wild stone spires, and the surf that we could both see and hear foaming and thundering on the steep beach […]

1881–1882, Robert Louis Stevenson, Treasure Island, London, Paris: Cassell & Company, published 14 November 1883

'But when the surf fell enough for the boats to get ashore, and Greening held a lantern for me to jump down into the passage, after we had got the side out of the tomb, the first thing the light fell on at the bottom was a white face turned skyward.

1898, J. Meade Falkner, chapter 5, in Moonfleet, London, Toronto, Ont.: Jonathan Cape, published 1934

It was alone, nervously alighting and flying short distances along the surf.

1900, Joseph Grinnell, Birds of the Kotzebue Sound Region, Alaska‎, page 12

In most instances the inshore holes or pockets along the surf do not produce as well as the cuts or sloughs between sand bars.

1941, Raymond Russell Camp, Fishing the Surf‎, page 248

Snook are found in rivers, canals, inlets and along the surf, especially around sand bars, tidal rips, jetties, bridges and piers.

1963, Vlad Evanoff, Spin Fishing‎, page 181

She [...] loves to cook, sew and dance. She's up on all the latest steps like the frug, the hully-gully and the surf.

1964 July 15, The Australian, Sydney, page 20, column 3

Such diversion as Podson could extort from his isolation was soon vitiated by repetition. He surfed. He sun-baked - with discretion till his skin had peeled and given him a harder cuticle.

1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, page 90