Hobbit-speech

At one time, Hobbits lived close to northern peoples of Men in the Vales of Anduin, where they shared a common Mannish language. As the years passed, events conspired to drive these two peoples apart: the Hobbits passed westward across the Misty Mountains, while the Northmen, after much travelling through Middle-earth, settled at last in the southern land that came to be called Rohan.

Among the Shire-hobbits, their old language was displaced by the Westron or Common Speech, but the Hobbits retained some of their old words (like smial or mathom, as well as the names of days and months). Because of their common heritage, the Hobbits who visited Rohan discovered that they could understand much of what was said in that land's ancestral language.

Tolkien represents this ancestral language of the Hobbits and Rohirrim as Old English: a suitable comparison, because that early Mannish speech formed a basis of the Westron in much the same way that Old English was a vital element in the evolution of modern English. That does not mean, of course, that Hobbits actually spoke Old English: they lived long, long before that language appeared. Hobbit-speech itself was quite distinct and alien in nature (to our ears), though little of the actual language survives apart from a few personal and place names.