Of Hobbits [ Appendix F ]
The Hobbits of the Shire and of Bree had at this time, for probably a thousand years, adopted the Common Speech. They used it in their own manner freely and carelessly; though the more learned among them had still at their command a more formal language when the occasion required.
There is no record of any language peculiar to Hobbits. In ancient days they seemed always to have used the languages of Men near whom, or among whom, they lived Thus they quickly adopted the Common Speech after they entered Eriador, and by the time of their settlement at Bree they had already begun to forget their former tongue. This was evidently a Mannish language of upper Anduin, akin to that o fthe Rohirrim; though the southern Stoors appear to have adopted a language related to Dunlendish before they came north to the Shire. [ The Stoors of the Angle, who returned to the Wilderland, had already adopted the Common Speech; but Deagol and Smeagol are names in the Mannish language of the region near the Gladden. ]
Of these in the time of Frodo there were still some traces left in local words and names, many of which closely resembled those found in Dale or in Rohan. Most notable were the names of days, months, and seasons; several other words of the same sort (such as mathom and smial) were also still in comon use, while more wre preserved in the place-names of Bree and the Shire. The personal names of Hobbits were also peculiar and many had come down from ancients.
Hobbit was the name usually applied by the Shire-folk to all their kind. Men called them Halflings and the Elves Periannath. The origin of the word hobbit was by most forgotten. It seems, however, to have been at first a name given to the Harfoots  by the Fallohides and Stoors, and to be a worn -down form of a word preserved more fully in Rohan: holbytla 'hole-builder.'