sacrum

American  

[sak-ruhm, say-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.

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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

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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

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Other Word Forms

Noun Inflected Forms

• sacra
  plural

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Etymology

Origin of sacrum

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

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Compare meaning

How does sacrum compare to similar and commonly confused words? Explore the most common comparisons:

• sacrum vs. coccyx

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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.

Example Sentences

See Examples For:

sacrum sacra

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 study, published in Analytical Chemistry, examined an exceptionally well preserved Edmontosaurus sacrum weighing 22 kilograms.

From Science Daily ● Aug. 14, 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

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

From Seattle Times ● May 15, 2024

Luz, luz, n. a bone supposed by Rabbinical writers to be indestructible, probably the sacrum.

From Chambers's Twentieth Century Dictionary (part 2 of 4: E-M) 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

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

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

In 1763 his first work, a perfunctory dissertation, De pyrologia sacra, first saw the light.

From Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 1 "Evangelical Church Conference" to "Fairbairn, Sir William" by Various

All new 500 discoveries made by the active Commissione di archeologia sacra are chronicled with as little delay as possible in the Nuovo Bulletino de archeologia cristiana published in Rome.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5 "Cat" to "Celt" by Various

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