The root, I apprehend, like that of most other river-names, is to be found in a verb signifying to move, to go—the Sansc. ar, ir or ur, Lat. ire, errare, &c. And we are not without an additional trace of the sense we want, as the Basque has ur, water, errio, a river, and the Hung. has er, a brook. The sense of swiftness, as found in Sansc. ara, may perhaps intermix in the following names. But there is also a word of precisely opposite meaning, the Gael. ar, slow, whence Armstrong, with considerable reason, derives the name of the Arar (or Saone), a river noted above all others for the slowness of its course. Respecting this word as a termination see page 11.

1.England.The Arrow, Radnor. The Arrow, Worcester.
The Ore. Joins the Alde.
Ireland.Arrow, lake and river, Sligo.
France.The Auray. Dep. Morbihan.
Germany.Ara, 8th cent. The Ahr, near Bonn, the Ohre, which joins the Elbe, and the Ohre in Thuringia, had all the same ancient name of Ara.
Ur(aha), 10th cent., now the Aur(ach).
Switzerland.Ara, ant. The Aar.
Italy.The Era. Joins the Arno.
Spain.Urius ant., now the Rio Tinte.
Russia.Oarus (Herodotus), perhaps the Volga.
2.With the ending en.
England.The Arun, Sussex.
Scotland.The Orrin and the Earne.
Ireland.The Erne, Ulster.
Germany.Oorana, 8th cent., now the Orre.
Arn(ape), 8th cent., (ap, water), now the Erft.
The Ohrn. Wirtemberg.
Tuscany.Arnus ant. The Arno.
3.With the ending el.
Germany.Erl(aha), 11th cent. The Erla.
Urula, 9th cent. The Erl.
Arla, 10th cent. The Arl.
The Orla. Joins the Saale.
Savoy.The Arly.
Aust. Slavonia.The Orly(ava).
Russia.The Ural and the Orl(yk).

From ar and ur, to move, the Sanscrit forms arch and urj, with the same meaning, but perhaps in a rather more intense degree, if we may judge by some of the derivatives, as Lat. urgeo, &c. In two of the three appellatives which I find, the Basque erreca, brook, and the Lettish urga, torrent, we may trace this sense; but in the third, Mordvinian (a Finnish dialect), erke, lake, it is altogether wanting. And on the whole, I cannot find it borne out in the rivers quoted below. Perhaps the Obs. Gael. arg, white, which has been generally adduced as the etymon of these names, may intermix.

1.England.The Arke. Yorkshire.
The Irk. Lancashire.
France.The Ourcq. Dep. Aisne.
The Orge and the Arc.
Belgium.The Herk. Prov. Limburg.
Sardinia.The Arc. Joins the Isère.
Spain.The Arga. Joins the Aragon.
Armenia.Aragus ant., now the Arak.
2.With the ending en.
Germany.Arguna, 8th cent. The Argen.
Russia.The Argun. Two rivers.
Spain.The Aragon. Joins the Ebro.
3.With the ending et.
Siberia.The Irkut. Joins the Angara.
4.With the ending es.
France.The Arques.
Russia.The Irghiz. Two rivers.
5.With the ending enz.[15]
Germany.Argenza, 9th cent., now the Ergers.

From the Sansc. ri, to flow, Gr. ῥεω, Lat. rigo (often applied to rivers—"Qua Ister Getas rigat," Tibullus), Sansc. rinas, fluid, Old Sax. rîha, a torrent, Ang.-Sax. regen, Eng. rain, Slav. rêka, a stream, Welsh rhe, rapid, rhean, rhen, a stream, &c., we get the following group. The river Regen Berghaus derives from Germ. regen, rain, in reference to the unusual amount of rain-fall which occurs in the Böhmer-wald, where it has its source. Butmann derives it from Wend. and Slav. rêka, a stream, connecting its name also with that of the Rhine. Both these derivations I think rather too narrow.

With respect to the Rhine I quote the following opinions. Armstrong derives it from Celt. reidh-an, a smooth water, than which nothing can be more unsuitable—the characteristic of the river, as noticed by all observers, from Cæsar and Tacitus downwards—being that of rapidity. Donaldson compares it with Old Norse renna, fluere, and makes Rhine = Anglo-Saxon rin, cursus aquæ. Grimm (Deutsch. Gramm.) compares it with Goth. hrains, pure, clear, and thinks that "in any case we must dismiss the derivation from rinnan, fluere." Zeuss and Förstemann support the opinion of Grimm; nevertheless, all three agree in thinking that the name is of Celtic origin. The nearest word, as it seems to me, is Welsh rhean, rhen, a stream, cognate with Sansc. rinas, fluid, Old Norse renna, fluere, and (as I suppose), with Goth. hrains, pure.

1.England.The Rea. Worcester.
The Wrey. Devonshire.
Ireland.The Rye. Joins the Liffey.
Germany.The Rega. Pomerania.
Holland.The Regge. Joins the Vecht.
Spain.The Riga. Pyrenees.
Russia.Rha ant., now the Volga.
2.With the ending en.
Germany.Regin, 9th cent. The Regen.
Rhenus, 1st cent. B.C. The Rhine.
The Rhin. Joins the Havel.
The Rhine. A small stream near Cassel.
Norway.The Reen.
Italy.The Reno by Bologna.
Asiat. Russ.The Rhion, ant. Phasis.

The Sansc. lî, to wet, moisten, spreads into many forms through the Indo-European languages. I divide them for convenience into two groups, and take first Lat. liqueo, Old Norse leka, Ang.-Sax. lecan (stillare, rigare), Gael. and Ir. li, sea, Gael. lia, Welsh lli, llion, a stream. Most of the following names, I take it, are Celtic. I am not sure that the sense of stillness or clearness does not enter somewhat into the two following groups.

1.England.The Lee. Cheshire.
The Leach. Gloucestershire.
Ireland.The Lee. Two rivers.
Germany.Licus, 2nd cent., now the Lech.
Lia, 8th cent., now the Luhe.
France.Legia, 10th cent., now the Lys.[16]
Belgium.The Leck. Joins the Maas.
Hindostan.The Lye. Bengal.
2.With the ending en = Welsh llion, a stream.
England.The Leen. Notts.
Scotland.The Lyon and the Lyne.
France.The Ligne. Dep. Ardéche.
3.With the ending er.
England.The Legre by Leicester, now the Soar.
France.Liger ant. The Loire.
The Legre. Dep. Gironde.

For the second group I take Lat. lavo, luo, Old Norse lauga, lavare, Anglo-Saxon lagu, water, Gael. lo, water, Gael. and Ir. loin, stream. In this group there may perhaps be something more of the Germain element, e.g., in the rivers of Scandinavia.