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sacrum

American  
[sak-ruhm, sey-kruhm] / ˈsæk rəm, ˈseɪ krəm /

noun

Anatomy.
  • sacra
    plural
  1. a bone resulting from the fusion of two or more vertebrae between the lumbar and the coccygeal regions, in humans being composed usually of five fused vertebrae and forming the posterior wall of the pelvis.


sacrum British  
/ ˈsækrəm, ˈseɪkrəm /

noun

  1. (in man) the large wedge-shaped bone, consisting of five fused vertebrae, in the lower part of the back

  2. the corresponding part in some other vertebrates

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

sacrum Scientific  
/ sā′krəm,săk′rəm /
  • sacra
    plural
  1. A triangular bone at the base of the spine, above the coccyx (tailbone), that forms the rear section of the pelvis. In humans it is made up of five vertebrae that fuse together by adulthood.

  2. See more at skeleton


Other Word Forms

Noun Inflected Forms

Etymology

Origin of sacrum

1745–55; < Late Latin ( os ) sacrum holy (bone), translation of Greek hieròn ostéon

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Explanation

The sacrum is the large, triangle-shaped bone at the base of the spine. Many, though not all, animals with a backbone also have a sacrum. In humans, the sacrum sits wedged between the two hip bones, connecting the lowest vertebra of the spine with the tailbone or coccyx. A man's sacrum is slightly different from a woman's: it's taller and narrower, with a larger curve. The word comes from the Latin phrase os sacrum, or "sacred bone," and it was named this way because the large sacrum of animals was often a part of ritual sacrifices in ancient times.

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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Deputies with the Humboldt County Sheriff’s Office identified it as a human sacrum, the triangular bone at the base of the spine, and submitted it to a state Department of Justice system of DNA samples.

From Los Angeles Times ● Sep. 21, 2026

The concept of a Christian “holy war”—a war conferring spiritual benefits—originates in medieval Latin Christianity, with its crusader theology of bellum sacrum.

From The Wall Street Journal ● Jun. 19, 2026

The fossil at the center of the study is a 22-kilogram Edmontosaurus sacrum, part of the dinosaur's hip region, recovered from South Dakota's famous Hell Creek Formation.

From Science Daily ● May 14, 2026

Woods said his sacrum had to be put back in place.

From Seattle Times ● May 15, 2024

They constitute a very serious and troublesome complication, and may occur on any part of the body subjected to pressure, but are most frequent over the sacrum and trochanters.

From A System of Practical Medicine by American Authors, Vol. I Volume 1: Pathology and General Diseases by Various

Most of the Boswellia sacra trees grow on public land, but custom dictates that each forest is given to one of the local families to farm, and Wadi Dawkah is his turf.

From BBC ● Feb. 9, 2010

With a practised flick, he cuts a strip of bark from the trunk of one of the Boswellia sacra trees.

From BBC ● Feb. 9, 2010

Warm winters and showery summers are the perfect conditions for the Boswellia sacra tree to produce the sap called frankincense.

From BBC ● Feb. 9, 2010

They are joined at the coccyges and sacra, and the spinal columns have nearly the same axis.

From Essays In Pastoral Medicine by Austin ?Malley

He has published it at length in his “Monumenta sacra inedita,” vol. v, vi, whence Tregelles derived its readings for the Pauline Epistles and the Apocalypse.

From A Plain Introduction to the Criticism of the New Testament, Vol. I. by Frederick Henry Ambrose Scrivener

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