From the second edition (1989):
grit, n.1
(grɪt) Forms: α. 1 gréot, 3, 5, 7, (9 dial.) gret, 3–4 greot, 4, (9 dial.) greit, 4, 7 grett, 4–8 grete, 4–9 greet, (5–7 greete, 7 griet, 8–9 dial. grate). β. 6 grite, gryt, 7– grit. [OE. gréot = OS. griot, OHG. grioȥ (MHG. grieȥ, G. griesz), ON. griót pebbles:—OTeut. *greutom, str. neut.; a pre-Teut. root *ghreud-: ghrud- appears in Lith. gruzti to crush, pound, Lettish grauds grain, OSl. gruda clod. The abnormal development of the vowel may be due to assimilation to grit n.2]

1. a. collect. sing. Formerly: Sand, gravel, small stones. Now: Minute particles of stone or sand, as produced by attrition or disintegration.

α Beowulf 3168 Forleton eorla estreon eorðan healdan, gold on greote, þær hit nu en lifað‥unnyt. a1000 Cædmon's Gen. 909 (Gr.) Þu scealt greot etan þine lifdaas. a1000 Andreas 425 (Gr.) Sand is eblonden, grund wið greote. a1300 Cursor M. 9938 (Cott.) Four strandes rinnes suete Thoru þat grauel and þat grett [other MSS. grete]. c1320 Sir Tristr. 2501 He fond awele [sc. a well] ful gode Al white it was, þe grete. ?a1500 Chester Pl. (Shaks. Soc.) I. 121 With grete gravill and greete I skoure an oulde pane. 1513 Douglas Æneis xii. Prol. 55 The syluer scalyt fyschis on the greit Ourthwort cleir stremis sprynkland for the heyt. 1639 G. Daniel Ecclus. xxv. 55 An Asscent straw'd wth a slippery greet. a1650 Dth. Robin Hood 100 in Furnivall Percy Folio I. 56 There make me a full fayre graue of grauell & of greete. 1655 Fuller Ch. Hist. i. v. §30 Small Griet and Gravell may choak a man. 1869 Lonsdale Gloss., Gret, fine gravel, sand. 1883 Almondbury & Huddersf. Gloss., Greet. 1887 S. Chesh. Gloss., Greit.
β 1589 Rider Eng.-Lat. Dict., Grite, or duste of stones or mettal, scobs. 1618 E. Elton Compl. Sanct. Sinner (1622) 239 Bread of deceit‥afterwards it turnes to grit and grauell in his mouth. 1657 R. Ligon Barbadoes (1673) 37 Though we wash it never so well, yet the grit cracks in our teeth. 1747 H. Glasse Cookery vi. 62 Take two or three Eels,‥and wash them from Grit. 1845 Florist's Jrnl. 218 A considerable quantity of road grit. 1865 Dickens Mut. Fr. ii. xv, The City grit gets into the hair and eyes and skin.

¶Used for grit n.2

a1225 Ancr. R. 70 Muche fol he were þe muhte, to his owene bihoue, hweðer se he wolde, grinden greot oðer hwete, ȝif he grunde þe greot & lefde þene hwete. ‘Hwete is holi speche’, ase Seint Anselme seið. Heo grint greot þe cheofled.

b. fig., with reference to the unpleasant or injurious qualities of grit.

1876 Lowell Among my Bks. Ser. ii. 184 It gives you a shock of unpleasant surprise, a kind of grit, as when one's teeth close on a bit of gravel in a dish of strawberries and cream. 1884 J. S. Brewer Hen. VIII, I. 105 The Venetian ambassador, gleeful as a schoolboy when he could throw grit into Wolsey's bread, was not sorry at the opportunity of carrying him the tidings. 1890 Spectator 13 Dec., Every tax is a handful of grit thrown into the machinery of industrial wealth, and impairs its productive powers.

c. A particle of sand. rare.

1601 Holland Pliny I. 314 If haply there doe arise a tempest‥they [bees] catch up some little stonie greet to ballaise and poise themselves against the wind. 1890 Abney Treat. Photogr. (ed. 6) 56 Application of acid may dissolve the grits away.

2. a. Coarse sandstone, esp. of the kinds used for millstones and grindstones; gritstone.

α c1275 Serving Christ 67 in O.E. Misc. 92 Me graueþ þis gode in greote and in ston. 1391 Mem. Ripon (Surtees) III. 109 In xvj petris de grete emp. pro j herthe. c1400 Siege Jerusalem (E.E.T.S.) 35/621 With grete stones of gret & of gray marble. 1587 Harrison England iii. ix. (1877) ii. 64 These [whetstones] also are divided either into the hard griet, as the common that shoomakers use, or the soft griet called hones. 1678 Hobbes Decam. x. 123 The Stone of which are made Milstones, which Stone is here called Greet. 1731 Lowthorp in Phil. Trans. Abr. I. viii. 588 The Portland stone is of a fine Chalky Greet, fit for all curious hewn and carved Work. 1747 Hooson Miner's Dict. M, Shale, Chirts, Greet, &c. do produce very good Veins, and that last very well likewise.
β 1710 Brit. Apollo III. No. 3. 2/1 A Grit or course free Stone. 1784 J. Belknap Tour White Mts. (1876) 20 Grind-stones are found at Fryeburg and at Amariscogin, of a fine grit, and hard. 1833 Lyell Princ. Geol. III. 222 The lacustrine strata are composed of gravel, grit and micaceous sandstone. 1851 Richardson Geol. (1855) 450 The upper beds consist of quartzose grits. 1874 Dawkins Cave Hunt. ii. 25 The massive millstone grit of Derbyshire and Yorkshire. 1882 Geikie Text Bk. Geol. ii. ii. §6. 158 By an augmentation in the size of the grains, a sandstone may become a grit, or a pebbly conglomerate sandstone.

b. Applied by J. Hill to a ‘genus’ of fossils.

1748 Sir J. Hill Hist. Fossils 569 Series III. Class IV. Order II. Genus I. Saburræ. Gritts. Fossils found in minute masses, forming together a kind of powder. Ibid., The white stony Gritts‥consisting of pure Spar.

3. Earth, soil, mould; †the ground, as under, in, on the greet. Now Obs. exc. dial.

c1250 Gen. & Ex. 3774 Erðe‥opnede vnder ere fet; Held up neiðer ston ne gret. a1300 Cursor M. 16923 Nu is þe croice grauen vnder greit, and iesus vnder stan. c1330 Amis & Amil. 1530 Graven in grete so cold. 1393 Langl. P. Pl. C. xiv. 23 As greyn that lyth in the greot and thorgh grace, atte laste, Spryngeth vp and spredeth. c1400 Melayne 1252 Many a Sarazene lay on his bake,‥Full Grisely gronande one the grete. ?a1500 Chester Pl. (E.E.T.S.) 405 Take we the body of this sweet, and lay it low under the greet! 1601 Holland Pliny I. 502 The blacke mould or grit. a1722 Lisle Husb. (1752) 6 The side lands in the hill country are always the poorest, because the good grete, or mold, is washed down by the rain. 1813 [see 6 below]. 1880 E. Cornwall Gloss., Greet, earth, soil.

4. The grain or texture of a stone, in respect of fineness, coarseness, etc.

1529 Rastell Pastyme, Hist. Brit. (1811) 105 These stonis at Stonehenge be all of one gryt, without chaunge of colour, or vayne. 1601 Holland Pliny II. 588 In this kind there be of a more free and softer grit. 1662 R. Mathew Unl. Alch. lxxxix. 154 Let not the sand be either too sharp or too fine, but of a middle greet. 1694 S. Foley in Phil. Trans. XVIII. 171 Of a whitish Free-stone colour, but a finer closer gret. 1776 G. Semple Building in Water 40 The Grit or Grain of it greatly resembled that of a Millstone. 1811 G. S. Keith Agric. Surv. Aberd. 56 (Jam.) When they mean to split it, they begin by drawing a straight line along the stone in the direction of its grete. a1835 Rickman Archit. App. (1848) 11 The ancient door is‥of‥a dark red sandstone of a strong grit.
fig. c1630 Risdon Surv. Devon §114 (1810) 118 There‥lived in this parish one Stone, who was of so hard a greete, that he lived to the age of one hundred and twenty years.

5. colloq. a. orig. U.S. slang. Firmness or solidity of character; indomitable spirit or pluck; stamina. to be clear grit, hard (etc.) grit: to have genuine spirit or pluck. to be the grit: to be the ‘right sort’, the genuine ‘article’.

1825 J. Neal Bro. Jonathan III. 386 Proper fellow he was too; 'cute enough, I tell you—sharp as a razor—clear grit. 1843 Haliburton Attaché II. i. 13 If he hadn't a had the clear grit in him, and showed his teeth and claws. 1861–2 Thackeray Philip xxxi, If you were a chip of the old block you would be just what he called ‘the grit’. 1863 Hawthorne Our Old Home (1883) I. 322 His main deficiency was a lack of grit. 1873–4 Dixon Two Queens III. xiii. ii. 12 John Fisher‥had not lost his northern grit and twang. 1880 Daily Tel. 7 Oct., Our English lads are hard grit. 1892 Times 23 Apr. 7/1 Every appointment of the kind must be based wholly upon fitness and grit.

b. In Canadian politics, a Radical or Liberal. Formerly clear grit.

1884 Fortn. Rev. May 592 There arose up [in Canada] a political party of a Radical persuasion, who were called Clear-Grits, and the Clear-Grits declared for the secularisation of the Clergy Reserves. 1887 Goldwin Smith in Contemp. Rev. July 15 The names ‘Tory’ and ‘Grit’, by which they call each other, therefore, being free from meaning, are really more appropriate than Conservative and Liberal, by which they call themselves. Ibid., Their leaders are more ready to accept baronetcies and knighthoods than the leaders of the Grits.

6. attrib. and Comb., as grit-ashlar, grit-band, grit-bed, grit-country, grit-getter; grit-tempered adj.; grit-berry, a name for the genus Comarostaphylis (Treas. Bot. 1866); grit-blasting vbl. n., the use of a stream of abrasive particles directed at a surface to clean it and roughen it; hence (as a back-formation) grit-blast v. trans. and absol.; grit-board dial., the earth-board of a plough; grit-cell = stone-cell (stone n. 20), sclereid; grit-emery, coarse emery; grit-rock = gritstone.

1855 Cornwall (1862) 77 The ‘best blue fine granite, or *grit-ashlar, for building sea-walls’. 1881 Geol. Mag. Nov. 488 The beds are traversed by a coarse cleavage dipping south, which usually ignores the hard *grit bands. 1890 Jrnl. Geol. Soc. XLVI. 496 The red slates with hard *grit beds south of Goodrington beach support a Triassic outlier. 1953 Arkell & Tomkeieff Eng. Rock Terms 53/1 The original sense of ‘gravelly’ seems to be preserved in the local term Grit Bed used for the Melbourn Rock in the Middle Chalk of Kent and Sussex, which is a band of limestone with a hard nodular structure. 1962 Flight International LXXXII. 201/1 The finished spar would be *grit-blasted,‥principally in order to remove small amounts of metal under closely controlled conditions. 1964 Financ. Times 8 Sept. 11/4 The operator can safely grit-blast without having to dress in protective clothing. 1936 Metals Handbk. (Amer. Soc. Metals) 841 (heading) Cleaning metals by blast cleaning process (also known as sand blasting, *grit, and shot blasting). 1947 Mettallurgia Apr. 279/2 Such a cleaning process as grit blasting lowers the corrosion resistance of the alloys. 1963 Times 22 Apr. p. v/1 To make sure the zinc sticks the steel must be roughened by gritblasting immediately beforehand. 1813 T. Davis Agric. Wilts 263 *Grate board, or bread Board—The mould or earth-board of a plough which turns the furrow; earth being frequently called grate. 1880 E. Cornwall Gloss., Greet-board, the earth-board of a plough. 1900 B. D. Jackson Gloss. Bot. Terms 115/2 *Grit-cell, a sclerotic cell, as in the flesh of pears. 1960 W. B. R. Laidlaw Guide Brit. Hardwoods 103 Fruit pear-shaped; with grit-cells. 1878 Davis & Lees West Yorksh. i. i. 14 The deep valleys in the *grit country usually have a stream at the bottom. 1884 F. J. Britten Watch & Clockm. 101 *Grit or corn Emery used for sharpening cutting burnishers. 1854 Illustr. Lond. News 5 Aug. 118 Occupations of the people,‥*Grit-getter. 1838 Penny Cycl. XI. 439/2 In the Carpathian mountains and in the Alps *grit-rocks with abundance of fuci (grès des Carpathes) represent the greensands of France and England. 1939 V. G. Childe Dawn Europ. Civilization (ed. 3) xii. 214 The ‘classical’ beaker‥made of relatively fine *grit-tempered ware. 1839 Stonehouse Axholme 189 Mr. Wesley was buried in Epworth churchyard under a plain *grit tombstone, supported by brick-work.