It may come as a great surprise to the fans of The Lord of the Rings, but the correct traditional spelling of the plural of “dwarf” is “dwarfs”, not “dwarves”. When an English noun ends with a single “f” in the singular, the “f” usually changes to “v” in the plural, as in:
There are, however, a few exceptions to the rule, e.g.
and “dwarfs” used to be one of the exceptions. Nonetheless, J. R. R. Tolkien decided to use the spelling “dwarves” throughout his books instead. Or did he?
Tolkien himself admitted that “dwarves” was a misspelling. In a letter to Stanley Unwin, the publisher of The Hobbit, he wrote (emphasis mine):
Modern usage of “dwarfs” and “dwarves”
The spelling may have started off as an error, but it has been living a life of its own and is now considered the standard spelling of the plural when referring to the fictional race created by Tolkien. Due to the books’ popularity, other fantasy authors commonly adopt the spelling as well. Take a look at the following graph showing the relative frequency of the nouns “dwarfs” and “dwarves” in English literature (created using Google Ngram Viewer):
When referring to the meanings of the word “dwarf” not related to fantasy, the plural “dwarfs” should be used, especially when referring to people:
and scientific objects: