[Usually cave in: in meaning identical with the dial. CALVE in (q.v.), and perh. phonetically descended from it (cf. hā’penny from half-penny); but even if so, it has certainly been associated with other senses of cave; cf. esp. CAVE v.1 ‘to hollow,’ CAVE v.2 ‘to fall all of a heap.’
(All the earliest instances of cave in, in print, are from America, and its literary use appears to have arisen there: but, as the word is given as East Anglian by Forby, 1830, and is widely used in Eng. dialects, it is generally conjectured to have reached the U.S. from East Anglia. Its history requires further investigation.]
1. To cave in: to fall in over a hollow, as the earth on the side of a pit or cutting; to fall in in a concave form, as when the front of a vertical section of earth or soil becomes concave in falling forward, from the greater weight or momentum of the higher part. Chiefly colloq.
1796. Morse, Amer. Geog., I. 398. The cellars are walled with brick … to prevent the loose sand from caving in.
1820. W. Irving, Sketch Bk. (1859), 196. As some labourers were digging to make an adjoining vault, the earth caved in, so as to leave a vacant space almost like an arch.
1848. Bartlett, Dict. Amer. (1860), To cave in, said of the earth which falls down when digging into a bank.
1863. Kingsley, Water-Bab., viii. 312. The roof caved in bodily.
1883. Manch. Guard., 18 Oct., 4/8. Two brothers … were at work … dismantling an old pit shaft, when a portion of the sides caved in and one of the men was partially buried.
2. fig. colloq. To yield to pressure from above, or from being morally or physically undermined; to break down, give way, give in, submit, collapse.
1848. New York Tribune, 4 March (Bartlett). [They] will cave in … though they talk loud against it now.
1851. T. Parker, Wks. (1863–71), VII. 372. Politician after politician ‘caved in’ and collapsed.
1855. Haliburton, Nat. & Hum. Nat., I. iv. 104 (Bartlett). He was a plucky fellow … and warn’t agoin’ to cave in that way.
1856. Kane, Arct. Expl., II. ix. 94. He felt so much better that he got up at six; but he caved in soon after.
1859. H. Kingsley, G. Hamlyn, xxviii. (D.). A puppy, three weeks old, joins the chase with heart and soul, but ‘caves in’ at about fifty yards, and sits him down to bark.
1880. J. Martineau, Hours Th., II. 268. The Romans … found their empire cave in for want of inward moral tension.
1887. Punch, 12 March, 132/1. In the end Government caved in, and unconditionally agreed to inquiry.
b. without in. slang.
1863. Reade, Hard Cash, I. 287. ‘Now I cave.’
¶ 3. trans. (causal.) To smash or ‘bash’ in. rare.
1870. Miss Bridgman, R. Lynne, II. v. 115. I should like to cave his head in.
Hence Cave-in sb.
1884. Boston (Mass.) Jrnl., 6 Sept. The most extensive cave-in that has occurred in this region for years, nearly one hundred acres of ground settling from four to six feet. [‘Common in Suffolk.’ F. Hall.]
