The website Manythings.com provides a list of English words that begin with the letter "B" totaling 1,146 in number. However, the list does not include all possible derivative words; for example, "belt" is included, but "belted" is not.
The difficulty in determining the true number of words that begin with the letter "B" begins with defining what constitutes a word. Some sources only count trunk words as words; others count all derivative words as well. Companies such as Colliers and Merriam-Webster redefine what are considered words on an annual basis, recognizing modern slang or conversational abbreviations as words periodically and increasing the potential number of words constantly.