waúrms, wurm; haúrn, horn; baúrgs (OHG. burg), city; waúrd, word; waúrpum, prt. pl. of waírpan, to throw (cp. [§ 32]); saúhts (OHG. suht), sickness; daúhtar, daughter; aúhsa, ox; taúhum, prt. pl. of tiuhan, to pul; baúhta, prt. of bugjan, to buy.
Note 1. aú before other sounds is entirely exceptional and sumwhat doutful. Thus, in auftô, perhaps (onse also ufto; Mt. XXVII, 64), bisauljan, to sully; bisaulnan, to becum sullied. Holtzmann (altd. gr., p. 14) regards also ufbauljan (II. Tim. III, 4) as belonging to this class.
Note 2. The change of short u into aú before h is without exception. An apparent exception is the enclitic -uh, and, the u of which must be referd to a secondary development; it is never found after a short accented vowel, nor after a long vowel or difthong; e. g., sa-h, ni-h, þai-h, wiljáu-h, ƕarjanô-h; u occurs after consonants, and in polysyllabic words in which a final short a before the u was elided; as, ƕaz-uh, þammuh (= þamma uh), qiþuh (= qiþa uh). Sum, however, assume -ûh (cp. Beitr. 18, 299).—Other us before h ar all long: þûhta (cp. [§ 15]).—There ar a few cases of u before r in unaccented syllabls ([§ 13], n. 1), namely in the foren words spaikulâtur and paúrpura (beside paúrpaúra), purpl; so, also, in the Gothic fidur- ([§ 141], n. 1) which, however, stands perhaps for fidûr- (cp. IF. 4, 334).—The prefix ur- (in urreisan, urruns, etc.) does not belong here; it is a late form for us the s of which was assimilated to a following r ([§ 78], n. 4).
Note 3. Not every au before h and r has developt from u, but may also be the difthong au; as, háuhs, high; táuh, prt. of tiuhan (but pl. taúhum, [§ 31]); gáurs, sorry (cp. OHG. gôrag, wreched, and Goth. gaunôn, to mourn).
Note 4. The au for u in the endings of the u-declension may be aú, but also áu which would be due to confusion caused by analogy. Beitr., 18, 280.—Cp. also uftô for auftô, [§ 24], n. 1.
Note 5. As a rule, the Greek ο is represented by aú; e. g., apaustaulus, ἀπόστολος; alabalstraun, ἀλάβαστρον; Barþaulaumaius, Βαρθολομαῖος; Pauntius, Πόντιος; aú = υ in Saúr, Σύρος; paúrpaúra, πορφύρα.—Goth. aú = o in the East Gothic name Thorisa. (Wrede, 'Ostg.', 76. 165).
§ [25]. II. The old difthong au [= ou in E. house]. Every au not broken from u (before h, r; s. [§ 24] and note 3) is a difthong; it corresponds to OHG. au, ou, or ô (ahd. gr., [§§ 45]. [46]), OS. ô, ON. au. Whenever it is likely to be confused with aú, we put (according to Grimm), an accute accent over the a (áu). E. g.
The prts. sg. of the II. ablaut-series ([§ 31]): gaut, I pour (inf. giutan); laug, I lied, etc.; laugnjan, to deny; daupjan, to baptize; galaubjan, to believ; galaubeins, belief; rauþs, red; dauþus, deth; —aukan, to increase; hlaupan, to run; stautan, to push, strike; —haubiþ, hed; augô, ey.
au in inflections and final occurs in the u-declension: sunaus, sunau; 1st pers. sg. opt.: nimau, nêmjau; 3d pers. sg. imper.: lausjadau; opt. midl: haitaidau.
Note 1. au often interchanges with aw (cp. [§ 42]); e. g., taujan, prt. tawida, to do; mawi, gen. maujôs, girl; sniwan, prt. snau, to hasten.