Protuberan is not a commonly used word and could potentially be misspelled due to its complex syllables. The correct spelling phonetically is [prəʊˈtjuːbərən], with emphasis on the second syllable "ju," and a silent "e" at the end. This word means to bulge out or protrude, and is often used in medical terminology to describe a swelling or a bump on the body. While its spelling may be challenging, it is an important vocabulary word in certain fields of study.