A is the first letter in all the alphabets of Phenician extraction. The Runic alphabet, being confused and arbitrary, makes the sole exception to this rule.
A. Pronunciation: it is either simple (a) or diphthongal (á). The simple a is pronounced long or short; when long it is sounded like the long Italian a as in padre, or as in Engl. father; when short, like the short Italian a as in cambio, or as in Engl. marry. The á—though in grammars commonly called a long vowel—is phonetically diphthongal (a + u), and sounds like Engl. ou or ow: Engl. thou and Icel. þá, now and ná, have almost the same sound. Again a and á have, like all other vowels, diphthongs or simple, a deep, full chest-sound if followed by a single consonant, or by more than one weak consonant (a liquid followed by a media). They sound short if followed by two or more strong consonants (a double mute or liquid): thus the a and á sound long in tāl, sermo; sāt, sedebat; mān, mancipium; tā̇l, dolus; ā̇r, remits; sā̇t, sessio, hātr, odium; hārðr, durus; kāldr, frigidus; vāndr, difficilis; tāmdr, domitus, etc. But short in hătt, pileum; hă̇tt, modum; mănn, bominem; bănn, interdictum; hă̇ll, lubricus; kălt, frigidum; rămt, acidum; hărt, durum; vănt, assuetum, etc.; the consonants shortening the sound of the preceding vowel. The a is also short in all endings, verbal or nominal, tālă, tālăr, tālăðă, dixi; tālăst, dicitur; vākă, vigilia; fāgrăn, pulchrum, etc. Etymologically a distinction must be made between the primitive á, as in sátu (sedebant), átu (edebant), gátu (poterant), and the á produced by suppressing consonants; either nasals, as in á, ást, áss, báss, gás, = an, anst, ans, bans, gans; or gutturals, h, g, k, as in á (aqua), sá (videbat), lá (jacebat), má (debet), nátt (nox), dráttr (tractus), and a great many others; or labials, v, f, as in á = af, áir = afr, hár but háfan; or dentals, as in nál (acus) [Goth. neþla, Engl. needle], vál (ambitus, mendicitas) [A. S. vädl], etc. In very early times there was no doubt an audible distinction between these two kinds of á, which however is not observed even by the earliest poets, those of the 10th century. The marking of the diphthongal vowels with an acute accent is due to the Icelandic philologist Thorodd (circa 1080–1140), and was probably an imitation of Anglo-Saxon. The circumflex, applied by Jacob Grimm, is unknown to Icel. authors of whatever age. Thorodd, in his treatise on the vowels (Skálda, pp. 160 sqq.), distinguishes between three kinds of vowels, viz. short, long (i. e. diphthongal), and nasal. The long ones he proposes to mark with an acute (´); the nasals by a dot above the line (˙). The vowels of his alphabet are thirty-six in number. According to his rule we should have to write, af (ex), át (esus), ȧ (in). No doubt the a was also nasal in the verbs and the weak nouns, komȧ (= koman), augȧ (gen.); and also when followed by an n, e. g. vȧnr (assuefactus). The distinctive marking of the nasals never came into practice, and their proper sound also disappeared; neither is this distinction observed by the poets in their rhymes. The marking of the diphthongal vowels—either the primitive vowels or those formed by agglutination—by an acute accent, according to the rule of Thorodd, is indeed used in a very few old Icel. parchment fragments of the 12th century. The only MS. of any considerable length which strictly observes this distinction is the Ann. Reg. Ísl. 2087. 4b. Royal Libr. Copenhagen, written in Icel. at the end of the 13th century. In the great bulk of MSS. both kinds of vowels are treated alike, as in Latin. About the middle of the 14th century the doubling of vowels, especially that of aa () = á, came into use, and was employed through more than three centuries, until about 1770 the Icelanders resumed the spelling of Thorodd, marking diphthongal vowels by an acute accent, but following the rules of modern pronunciation. The diphthong au—in Norse freq. spelt ou—has at present in Icel. a peculiar sound, answering to äu or eu in German, and nearly to Engl. oi. The Norse pronunciation is different and perhaps more genuine.
B. Changes. I. a changes into e, á into æ: this change—a part of a more general transformation, by Grimm termed umlaut, ‘vowel-change’—is common to all the Teutonic idioms, except the Gothic (v. letter E and Æ). II. a changes into ö (), á into ́: this transformation is peculiar to the Scandinavian branch, esp. the Icelandic idiom, where it is carried on to the fullest extent—in old Swedish and Danish its use was scanty and limited. It takes place, 1. in monosyllabic nouns with a for their radical vowel, α. feminines, öld, periodus; önd, anima; örk, arca; för, iter; höll, aula; hönd, manus; sök, causa, etc. β. adjectives in fem. sing. and in neut. pl., öll, tota; fögr, pulchra; hörð, dura; hölt, clauda; sönn, vera; from allr, etc. γ. in plur. neut., bönd, vincula; börn, τέκνα; lönd, terrae; from band, etc. δ. in singular masculines with a suppressed u in the root, hjörtr, cervus; fjörðr, sinus; björn, ursus; örn, aquila, etc. 2. in dissyllables a radical a, when followed by a final u (-u, -ur, -um, etc.), in Icel. constantly changes into ö,—öllum, cunctis; mönnum, hominibus; köllum, vocamus; vökum, vigiliis and vigilamus; vökur, vigiliae, etc. Danes and Swedes here retained the a; so did a great part of Norway. The change only prevailed in the west of Norway and the whole of Iceland. Some Norse MSS. therefore constantly keep a in those cases, e. g. Cd. Ups. De la Gard. 8 (Ed. C. R. Unger, 1849), which spells allum, cunctis; hafuð, caput; jafur, rex; andverðr, adversus; afund, invidia, etc. (v. Pref. viii.) Other Norse MSS. spell a and ö promiscuously; allum or öllum, kallum or köllum. In Icel. this change prevailed about the year 1000. Even at the end of the loth century we still frequently meet with rhymes such as barð—jarðu, þang—langu, etc. 3. a in inflexions, in penultimate syllables, if followed by u, changes into u (or ö); thus keisurum, caesaribus; vitrurum, sapientioribus; hörðurum, durioribus; hörðustum, durissimis: pret. pl., sköpuðu, creabant; töluðu, dicebant; orrustu, pugnam. In part. pass. fem. sing. and neut. pl., sköpuð, creata; töluð, dicta; töpuð, perdita. Neut. pl. in words, as sumur, aestates; heruð, pagi. This change is peculiar to Iceland, and is altogether strange to Norse MSS., where we constantly find such forms as ætlaðu, putabant; gnagaðu, mordebant; aukaðu, augebant; skapað, creata; kallað, dicta; skaparum, tapaðum, ágætastum, harðarum, skínandum; kunnastu, artem, etc. This difference, as it frequently occurred at early times, soon gave the Icel. idiom a peculiar and strange sound,—amarunt would, in Icelandic, be ömurunt. Norse phrases—as með bænum ok fastu (föstu) hafðu (höfðu) með sér vaxljós, ok dýrkaðu (dýrkuðu) þa hælgu hátíð með fastu (föstu) ok vaktu (vöktu) þar um nóttina með margum (mörgum) aðrum (öðrum) vanfærum mannum (mönnum), O. H. L. 87—sound uncouth and strange to Icel. ears; and so no doubt did the Icel. vowel transformations to Norse ears. 4. endings in -an, -all, e. g. feminines in -an, as hugsan, ætlan, iðran, frequently change into -un,—hugsun, ætlun, iðrun, and are now always used so: gamall, vetus, f. gömul; einsamall, solus, f. einsömul. In modern Norse, gomol, eismol (Ivar Aasen); atall, atrox; ötull, strenuus; svikall, perfidus, and svikull; þrifnaðr, mundities, and þrifnuðr, etc. 5. in the cases correlative to II. 1, 2, the á in its turn changes into a vowel, by Thorodd marked ́; this vowel change seems to have been settled about the beginning of the 11th century, and prevailed in Iceland during the 12th, being constantly employed in MSS. of that time; about the end of that century, however, and the beginning of the next, it fell off, and at last became extinct. Its phonetical value, therefore, cannot now be precisely stated: it no doubt had an intermediate sound between á and ó, such as ö () has between a and o. Thorodd proposed to mark the short ‘umlaut’ ö by ; and the vowel change of á by ́ (in the MSS. however commonly written ǫ). Instances: fem., ́, amnis; ́st, amor; ́l, funis; ́r, remits; ĺg, lignum; skŕ, libellus; śtt, pax; śl, anima; ńl, acus; v́n, spes: masc., h́ttr, modus; þŕðr, filum; þ́ttr, funis; ḿttr, vis; ́ss, deus; ́rr, nuntius: neut. pl., śr, vulnera; t́r, δάκρυα; ḿl, dicta; ŕð, consilia; v́r, vera: adj. fem, and neut., ḱt, læta; f́, pauca; sḿ, parva; h́, alta; f́m, paucis; h́m, altis: verbs, ś, videbant (but sá, videbat); ǵtu, capiebant; ́tu, edebant (but át, edebat), etc.: v. Frump. 26–28: e. g. sár (vulnus) veitti maðr mér eitt (unum), śr mörg (multa vulnera) veitta ek hánum, Skálda (Thorodd), 162; l (= öl, cerevisia) er drykkr, ́l er band (vinculum), id. 163; tungan er málinu vn (= vön, assuefacta), en at tönnunum er bitsins v́n (morsils exspectatio), id.: frequently in the Grágás, lýsa sár sitt (vulnus) eðr śr (vulnera) ef fleiri eru, Kb. i. 151; śr en minni (vulnera leviora), 170; en meire śr (graviora), 174; síðan es śr eða ben voru lýst, 175; engi śr (nulla vulnera), śr, and ŕð, 176, 177; ḿl, ii. 51; v́r, 158, etc.
C. Other Changes:—in modern Icel. the old syllable vá has changed into vo; vó of the 14th century being an intermediate form: thus von, spes; votr, madidus; vor, ver; vorr, noster; voði, periculum; koma, adventus; voru, erant, etc.: so also the á in the dat. hánum, illi, now honum, which is also employed in the editions of old writings; kómu = kvámu = kvómu, veniebant, etc. In Norway a was often changed into æ in the pronominal and adverbial forms; as hæna, illam; þær, þænn, þæt, ibi, ilium, illud; hence originate the mod. Dan. hende, der, den, det; in some Norse dialects even still dar, dat. The short a in endings in mod. Dan. changed into e (æ), e. g. komme, uge, talede, Icel. koma, vika; whereas the Swedes still preserve the simple a, which makes their language more euphonious than the mod. Dan. In most districts of Icel. an a before ng, nk, has changed into á, thus langr (longus), strangr (durus), krankr (aegrotus) are spelt lángr, kránkr, etc. In the west of Iceland however we still say langr, strangr, etc., which is the pure old form. The a becomes long when followed by lf, lm, lp, thus álfr, genius; álpt, cygnus; hálfr, dimidius; kálfr, vitulus; sjálfr, ipse; this is very old: the fem. hǫlf, dimidia, which occurs in the 12th century, points to an á, not a; já = ja in hjálpa, skjálfa, etc. The lengthening before lm is later,—álmr, ulmus; hálmr, calamus; sálmr, psalmus; hjálmr, galea; málmr, metallum, etc. In all these cases the á is not etymological. Also before ln in the plur. of alin, álnar not alnar: lk, alka = alka, alca; bálkr = balkr; fálki = falki, falco: háls = hals; frjáls = frjals; járn = jarn; skáld = skald; v. those words: aarni, dat. of arinn, v. that word: the proper name Árni, properly Arni: abbati, abbas, ábóti: Adám, on the contrary, changed into Adam; Máría into Maria, Mary. The old spelling is still kept in máriatla, motacilla pectore albo, etc. In the 1st pers. pret. indic., and in the pres. and pret. conj. we have a changed into i, e. g. talaða to talaði, locutus sum; sagða, dixi, vilda, volui, hafða, habui, to sagði, vildi, hafði: in the 1st pers. pres. and pret. conj., hefða, haberem, hafa, habeam, to hefði, hafi. These forms occur as early as the beginning of the 13th century (e. g. in the Hulda, Cd. A. M. 66, fol. = Fms. vi. and vii). In the south of Iceland however (Reykjavík, the Árnes and Gullbringusýsla) the old forms are still frequently heard in bisyllabic preterites, esp. ek vilda, sagða, hafða, and are also employed in writing by natives of those districts.
D. a answers to Goth. a; A. S. ea (a, ä); allr, totus; Goth. alls; A. S. eall: the primitive á to Goth. ê, sátu, Goth. sêtun, sedebant; gráta, grétun, lacrymari; láta, lêtan; vápn, vêpn, arma; vagr, vêgs, fluctus. The Icel. secondary á, on the contrary, must in the kindred Teutonic idioms be sought for under a vowel plus a consonant, such as an, ah, or the like. A. S. æ commonly answers to Icel. á, láta, A. S. lætan; dáð, A. S. dæð; þráðr, A. S. þræð, Engl. thread; mál (καιρύς), A. S. mæl, cp. Engl. meal. The A. S. æ, on the contrary, etymologically answers to Icel. ei. The diphthong au answers to Goth. au, A. S. eá,—rauðr, Goth. rauds, A. S. reað, Engl. red. In English the a seems at very early times to have assumed its present ambiguous sound; this we may infer from A. S. words introduced into Icelandic. The river Thames in Icel. is spelt, as it is still pronounced in England, as Tems, which form occurs in a poem of the year 1016.
E. The Runic character for a was in the Gothic and Anglo-Saxon Runes (so termed by P. A. Munch) ᚨ [A. S. ᚩ]; so in the Golden horn, on the stone in Thune in Norway (Ed. by P. A. Munch, 1857), and in the Bracteats. The Saxons called it ôs = áss, deus. In the Runes it was the fourth letter in the first group (fuþork). The Scandinavians in their Runes used this character for o, and called it óss, ostium, probably misled by the A. S. pronunciation of the homely word áss. This character, however, occurs only a few times in the common Runes, which in its stead used the A. S. Rune j, gêr, annona, which is the fourth Rune in the second group (hnias, A. S. hnijs), called according to the northern pronunciation ár, annona: this letter, ᛆ or ᛅ has the form, as well as the name and place, of the A. S. j, ᛄ.