Translation according to P. W. Joyce:
Inish, an island. See vol. i. p. 440 [reproduced below].
The most common word for an island is inis, genitive inse, insi, or innsi, cognate with Welsh ynys. Arm. Enes, and Lat. Insula: the form insi or innsi is sometimes used as a nominative even in the oldest and best authorities (see p. 33, sect. vii.). It is also applied in all parts of Ireland to the holm, or low flat meadow along a river; and a meadow of this kind is generally called an inch among the English-speaking people, especially in the south. This, however, is obviously a secondary application, and the word must have been originally applied to islands formed by the branching of rivers; but while many of these, by gradual changes in the river course, lost the character of islands, they retained the name. It is not difficult to understand how, in the course of ages, the word inis would in this manner gradually come to be applied to river meadows in general, without any reference to actual insulation. The principal modern forms of this word are Inis, Inish, Ennis, and Inch, which give names to a vast number of places in every part of Ireland; but whether, in any individual case, the word means and island or a river holm, must be determined by the physical configuration of the place. In many instances places that were insulated when the names were imposed are now no longer so, in consequence of the drainage of the surrounding marshes or lakes; as in case of Inishargy (p. 410). Inis and Inish are the forms most generally used, and they are the common appellations of the islands round the coast, and in the lakes and rivers; they are also applied, like inch, to river meadows. There is an island in Lough Erne, containing the ruins of an ancient church, which the annalists often mention by the name of Inis-muighe-samh [moy-sauv], the island of the plain of the sorrel; this island is now, by a very gross mispronounciation, called Inishmacsaint, and has give name to the parish on the mainland. Near the town of Ennis in Clare, is a townland called Clonroad, which preserves pretty well the sound of the name as we find it in the annals, Cluain-ramhfhoda, usually translated the meadow of the long rowing: the spot where Ennis now stands must have been originally connected in some way with this townland, for the annals usually mention it by the name of Inis-Cluana-ramfhoda, i.e. the river meadow of Clonroad. Inishnagor in Donegal and Sligo, is a very descriptive name, signifying the river meadow of the corrs or cranes; there are several places in both north and south, called Enniskeen and Inishkeen, in Irish Inis-caein (Four Mast.), beautiful island or river holm. Inistioge in Kilkenny is written Inis-Teoc in the Book of Leinster, Teoc's island; and Ennistimon in Clare is called by the Four Masters Inis-Diomain, Diman's river meadow. This word very often occurs in the end of names, usually forming with the article the termination nahinch; as in Coolnahinch, the corner or angle of the island or river meadow. Sometimes it is contracted, as we see in Cleenish, an island near Enniskillen, giving name to a parish, which ought to have been called Cleeninish; for the Irish name, according to the Four Masters, is Claen-inis, i.e. a sloping island.