ex·​os·​to·​sis ˌek-(ˌ)sä-ˈstō-səs How to pronounce exostosis (audio)
plural exostoses ˌek-(ˌ)sä-ˈstō-ˌsēz How to pronounce exostosis (audio)
: a spur or bony outgrowth from a bone or the root of a tooth

Examples of exostosis in a Sentence

Recent Examples on the Web The opinion was unanimous that these were tori, also called exostoses, a benign type of bony overgrowth of the jaw. Dr. Keith Roach, oregonlive, 26 Jan. 2023 An exostosis forms when the ears’ delicate tissues are repeatedly irritated over long periods of time. Nathaniel Scharping, Discover Magazine, 14 Aug. 2019 The dense growths are known as external auditory exostoses. Ashley Strickland, CNN, 14 Aug. 2019 Cold Water Love catching waves? Surfers and other cold water swimmers are prone to something called exostoses, or small bony growths in the ear canal that develop slowly over time and can prevent sound from getting in. Clare Thorp, Cosmopolitan, 2 Aug. 2017 Riley was born with a genetic condition called hereditary multiple exostoses (HME), which causes irregular bone growth. George Diaz, OrlandoSentinel.com, 4 July 2017

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'exostosis.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin, from Greek exostōsis, from ex out of + osteon bone — more at ex-, osseous

First Known Use

1736, in the meaning defined above

Time Traveler
The first known use of exostosis was in 1736

Dictionary Entries Near exostosis

Cite this Entry

“Exostosis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/exostosis. Accessed 21 Jun. 2024.

Medical Definition


ex·​os·​to·​sis ˌek-(ˌ)säs-ˈtō-səs How to pronounce exostosis (audio)
plural exostoses -ˌsēz How to pronounce exostosis (audio)
: a spur or bony outgrowth from a bone or the root of a tooth
exostotic adjective

More from Merriam-Webster on exostosis

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