coccyx
Americannoun
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a small triangular bone forming the lower extremity of the spinal column in humans, consisting of four ankylosed rudimentary vertebrae.
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a corresponding part in certain animals.
noun
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A small triangular bone at the base of the spine in humans and apes. It is composed of several fused vertebrae.
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Also called tailbone
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Etymology
Origin of coccyx
1605–15; < New Latin < Greek kókkyx cuckoo, from its resemblance to a cuckoo's beak
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Vocabulary lists containing coccyx
Example Sentences
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The boy was fifteen, skinny, almost malnourished, so that the hip bones and coccyx stood out sharply.
From The Wall Street Journal ● Nov. 11, 2025
Following this evolutionary split, the group of apes that includes present-day humans evolved the formation of fewer tail vertebrae, giving rise to the coccyx, or tailbone.
From Science Daily ● Feb. 28, 2024
The coccyx is typically 3–4 vertebrae that fuse into one.
From Textbooks ● Jun. 9, 2022
The spinal column is composed of the seven cervical vertebrae, the nine thoracic vertebra, the four lumbar vertebrae, the sacrum, and the coccyx.
From Textbooks ● Jan. 1, 2015
The os coccyx in man, though functionless as a tail, plainly represents this part in other vertebrate animals.
From The Descent of Man and Selection in Relation to Sex, Vol. I by Darwin, Charles
The twins are joined only by the latero-posterior aspects of the sacra and coccyges, so that the two individuals are placed almost back to back.
From Essays In Pastoral Medicine by ?Malley, Austin
They are joined at the coccyges and sacra, and the spinal columns have nearly the same axis.
From Essays In Pastoral Medicine by ?Malley, Austin
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
