From the second edition (1989):
(bʊə(r)) Forms: (5 boueer), 6–7 boore, bour, (7 bore, boar), 7– boor (9 bauer). [A word of involved history in and out of English, though the ultimate etymology is clear enough. The 16th c. bour, boore, may possibly have been native Eng., repr. an earlier *búr, short for OE. ebúr ‘dweller, husbandman, farmer, countryman’ (Bosw.), a deriv. of búr ‘dwelling, house, cottage, bower’, f. the verb root, b to dwell: cf. the compound neighbour:—ME. neȝebur:—OE. néahebúr ‘nigh-dweller’, also modern East Anglian bor ‘neighbour’ as a form of address. But on the whole, in its literary use, the word is more likely to have been adopted from LG. bûr, Du. boer: see the quots. under sense 2, and Boer. These words are themselves etymological equivalents (or nearly so) of OE. ebúr; the OHG. form being gibûr, gibûro, MHG. gebûr, gebûre, MLG. gebûr, and bûr (occurring 1365), mod.LG. buur (made bauer in mod.HG.), MDu. ghebure, ghebuer, and buer; also (late) geboer, which was not properly a Du. form, but probably, according to Cosijn, adopted from Frisian, or, according to Franck, from the LG. on the eastern frontier of the Netherlands. This last is in mod.Du. boer. The original sense of WGer. gibûr, gibûro, was ‘inmate of a bûr or bower, fellow-occupier of a dwelling, farm, or village; neighbour, mate’. Partly from being preserved mainly in rural use, but largely from association with the vb. bûan (MHG., MDu. bûwen, Ger. bauen, Du. bouwen) to inhabit, cultivate, till (of which, as we have seen, it was not a derivative, though a cognate word from same root b-), its original connexion with bûr, bower, was lost, and the sense more and more confined to that of ‘peasant, rustic’, and thence ‘clown’.
While mod.Ger. has merged the word in form with bauer, agent-noun from bauen ‘to cultivate, to build’, mod.Du., on the contrary, makes a distinction in use between the native buur (MDu. ghebure, ghebuer) ‘neighbour’, and the adopted boer (MDu. geboer) ‘peasant, husbandman, farmer, clown, knave at cards’, and keeps both distinct from bouwer ‘tiller, builder’ (though in MDu. the latter was used in senses subsequently taken up by geboer, boer.]

1. A husbandman, peasant, countryman. Obs., exc. as in sense 3, into which it passes in later use.

[1430: see bower n.5] 1551 Turner Herbal (1568) Aiiijb, Absinthium rusticum, that is bouris or pesantes wormwode. 1592 R. Johnson 9 Worthies Biv, A countrie Boore, a goodlie proper swayne. 1611 Shakes. Wint. T. v. ii. 173 Not swear it?‥ Let Boores and Francklins say it, Ile sweare it. 1762 Hume Hist. Eng. (1806) III. App. iii. 633 Some remains of the ancient slavery of the boors and peasants. 1798 Malthus Popul. (1878) 326 While the land is cultivated by boors. [1820 Scott Monast. xxxvii, Times of action make princes into peasants, and boors into barons. 1850 Mrs. Browning Vis. Poets, Poems I. 204 The boor who ploughs the daisy down.]

2. Particularly, a Dutch or German peasant. (For the latter more definitely bauer occurs.)

1581 J. Bell Haddon's Answ. Osor. 254 To accuse Luther for the uproares raysed by the countrey Boores in Germany. 1612 Woodall Surg. Mate Wks. (1653) 58 My self chanced in Holland into the house of a Bore (as they term him) to lodge. 1642 Fuller Holy & Prof. St. ii. xviii. 116 Germany hath her Boores, like our Yeomen. 1645 E. Pagitt Heresiogr. (1662) 3 Upon this his preaching, about 40000 Bores and Trades-men rose up in Suevia. 1675 Lond. Gaz. No. 977/3 The Bores, assisted with 800 Spanish Soldiers. 1756 Nugent Gr. Tour, Netherl. I. 41 The people of Holland may be divided into five classes. 1. The boors or husbandmen. 1800 Coleridge Piccolom. i. ii, The Boors Can answer fresh demands already [= der Bauer kann Schon wieder geben]. 1860 Motley Netherl. (1868) II. ix. 11 Guarded by fifty men mostly boors of the country. [1879 Baring-Gould Germany I. 50 Lands were divided and sub~divided till the owners sank from being nobles to bauers.]

b. A Dutch colonist in Guiana, South Africa, etc. (For the latter Boer is now employed.)

1824 W. J. Burchell Trav. I. 13 The Boors must be heard, the Hottentots must be heard. 1832 H. Martineau Demerara ii. 23 The state of a boor as to health, comfort and security of property. 1834 Pringle Afr. Sk. iv. 184 Few but the very poorest boors.

c. Extended to foreign peasants generally.

1687 Cleveland Rustick Ramp. 488 What Boars of other Countrys could have compared with the Riches of our Peasants. 1764 Goldsm. Trav. 3 The rude Carinthian boor. 1798 Canning in Anti-Jacobin 12 Mar., Russian boors that daily kick. 1798 Malthus Popul. ii. iii. (1806) I. 368 The fortune of a Russian nobleman is measured by the number of boors that he possesses.

3. A peasant, a rustic, with lack of refinement implied; a country clown.

1598 Marston Pygmal. ii. 142, I dull-sprighted fat Boetian Boore. c1610 Rowlands Terrible Batt. 38 A paltry rusticke peasant boore. 1750 Wesley Wks. (1872) II. 207 Three or four boors would have been rude, if they durst. 1871 R. Ellis Catullus xxii. 14 A dunce more boorish e'en than hedge~born boor. 1874 Sayce Compar. Philol. viii. 336 The country boor is blind to the beauties of nature.

b. fig. Any rude, ill-bred fellow; a ‘clown’.

1598 Florio, Grossolano, a lubber, a clowne, a boore, a rude fellow. 1723 De Foe Col. Jack (1840) 4 He was as to manners a mere boor or clown. 1849 Miss Muloch Ogilvies i. (1875) 4 Hugh Ogilvie is a common-place, stupid boor. 1872 Black Adv. Phaeton xiii. 177 An ill-conditioned boor, not fit for the society of well-bred ladies.

4. boor's mustard. [ad. early mod.Ger. baurensenfe peasant's mustard.] A name given by herbalists (since Turner) to Thlaspi arvense, a British wild plant; by Gerard to Lepidium ruderale.

1548 Turner Names of Herbes, Thlaspi‥is called in duche Baurensenfe‥It may be named in englishe dysh-mustard, or triacle Mustard, or Boures Mustard. 1578 Lyte Dodoens 628 Turner calleth Thlaspi‥Bowers mustarde. 1597 Gerard Herbal 204/5 Bowiers or Bowyers mustard. 1878 Britten & Holl. Plant-N., Boor's mustard.