Translation according to P. W. Joyce:
Tulrush in Galway and Roscommon ; Tul-ruis, hill of the wood (ros: vol. i. pp. 443, 495 [reproduced below]).
The word ros signifies, first, a promontory or peninsula; secondly, a wood; and it has other significations which need not be noticed here. Colgan translates it nemus in Act. SS, p. 791 b, n. 15; and in Tr. Th., p. 383, a, n. 17, it is rendered peninsula. By some accident of custom, the two meanings are now restricted in point of locality; for in the southern half of Ireland, ros is generally understood only in the sense of wood, while in the north, this application is lost, and it means only a peninsula. Yet there are many instances of the application of this term to a peninsula in the south, showing that it was formerly so understood there. A well-known example is Ross castle on the lower lake of Killarney, so called from the little ros or point on which it was built. Between the middle and lower lakes is the peninsula of Muckross, so celebrated for the beauty of its scenery, and for its abbey; its Irish name is Muc-ros, the peninsula of the pigs; which is also the name of a precipitous headland near Killybegs in Donegal, and of several other places. And west of Killarney, near the head of Dingle bay, is a remarkable peninsula called Rossbehy or Rossbegh, the latter part of which indicates that it was formerly covered with birch trees: - birchy point. There is a parish in Leitrim called Rossinver, which takes its name from a point of land running into the south part of Lough Melvin - Ros-inbhir, the Peninsula of the inver or river mouth; and Rossorry near Enniskillen is called in the Four Masters, Ros-airthir [Rossarher], eastern peninsula, of which the modern name is a corruption. Portrush in Antrim affords an excellent illustration of the use of this word; it takes its name from the well-known point of basaltic rock which juts into the sea: - Post-ruis, the landing-place of the peninsula. The district between the bays of Gweebarra and Gweedore in Donegal is called by the truly descriptive name, The Rosses, i.e. the peninsulas. While it is often difficult to know which of the two meanings we should assign to ros, the nature of the place not unfrequently determines the matter. Rush north of Dublin, is called in Irish authorities Ros-eó [Rush-o], from which the present name has been shortened; and as the village is situated on a projection of land three-fourths surrounded by the sea, we can have no hesitation about the meaning of the first syllable: the whole name therefore signifies the peninsula of the yew-trees.
Ros, as I have already stated, has several meanings, one of which is a wood; and in this sense we often find it in names, especially in the south. There is a place called Rosserk near Killala at the mouth of the Moy in Mayo. It is called in Irish Ros-Serce (Serce's wood), and we learn from Mac Firbis (Hy Fiachrach, p. 51) that "it is so called from Searc the daughter of Carbery, son of Awley (see p. 139, supra), who blessed the village and the wood which is at the mouth of the river Moy." The original church founded by the virgin saint Searc in the sixth century, has long since disappeared; but the place contains the ruins of a beautiful little abbey. Roscrea in Tipperary is written in the Book of Leinster, Ros-Cre, Cre's wood. Roskeen, the name of several places, represents the Irish Ros-caein, beautiful wood. New Ross in Wexford, notwithstanding its name, is an old place; for Dermot Mac Murrough built a city there in the twelfth century, the ruins of which yet remain. It is called in the annals Ros-mic-Treoin [Rosmicrone], the wood of the son of Treun, a man's name; the people still use this name corrupted to Rosemacrone; and they think the town was so called from a woman named Rose Macrone, about whom they tell a nonsensical story. St. Coman, from whom was named Roscommon (Coman's wood), founded a monastery there, and died, according to the Four Masters, in 746 or 747, but other authorities place him much earlier. Ross Carbery in Cork, was formerly a place of great ecclesiastical eminence; and it was "so famous for the crowds of students and monks flocking to it, that it was distinguished by the name of Ros-ailithir" [allihir: Four Masters], the wood of the pilgrims. Rusheen, a diminutive, and the plural Rusheens, are the names of a great many townlands in Munster and Connaught; the word is often applied to a growth of small bushy trees or underwood, as well as to a wood small in extent. The word ros is often written with a instead of o, both in old records and in anglicised names; as in Rasheen Wood, near the Dundrum station of the Great Southern and Western Railway.