Forms: see TRIPLE a.; also 5 threpil, -el, tryple. [ad. med.L. triplāre (see TRIPLATE); cf. F. tripler (1484 in Godef., Compl.), Prov. triplar.]
1. trans. To make three times as great or as many as before; to multiply by three; to make threefold; to treble.
1375. (MS. 1487) Barbour, Bruce, XVIII. 30. And said, that he suld fecht that day, Thouch Tryplit or quadruplit [Edin. MS. (1489) tribill and quatribill] war thai.
a. 1400–50. Alexander, 1476. Þe bischop … Comandis to ilka creatour to crie þurȝe þe stretis, To thre dais on a thrawe be threpild [v.r. threpelytt] to-gedire.
1542. Recorde, Gr. Artes (1575), 115. To double the remayner of poundes, and triple the remayner of shillings.
1564. Reg. Privy Council Scot., I. 297. Thair abone impresonment to be tripled.
1620. in Foster, Eng. Factories Ind. (1906), 208. Private traders … who confesse they triple their principall between that place and Bantam.
1655. Clarke Papers (Camden), III. 23. His Highnesse … tripled the guards, and scoured the citty and 4 miles round with horse.
a. 1774. Goldsm., Surv. Exp. Philos. (1776), I. 128. The body goes on with the double impression, and receives also a new one which triples it.
1795. Hist., in Ann. Reg., 17/1. She was determined to double and even triple her army.
1820. Lamb, Elia, Ser. I. Two Races of Men. He will return them [books] … with usury; enriched with annotations, tripling their value.
1858. Buckle, Civiliz. (1864), II. i. 119. The export of foreign commodities was tripled.
b. To fold in three thicknesses. rare–0.
1573–80. Baret, Alv., T 376. Triple, to … fold a thing three times.
c. spec. in Mech. To alter (a steam-engine) from single or double expansion to the triple-expansion type; also, to fit (a vessel, etc.) with triple-expansion engines.
1891. [see TRIPLING vbl. sb. 1 b].
2. To amount to three times as many as. rare–1.
1589. in Hakluyt, Voy. (1599), II. II. 145. Their losse I can assure you did triple ours, as well in quality as in quantity.
3. intr. To grow to three times the former number or amount.
1799. W. Taylor, in Monthly Rev., XXVIII. 526. Our author hesitates whether wages have not tripled.
1805. Syd. Smith, in Lady Holland, Mem. (1855), II. 15. I … was pleasing myself with the notion … that your income was tripling and quadrupling in value.
1839. Times, 11 June. Within the last twenty years it [crime] has tripled.
