sacrum

American  

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

noun

Anatomy.

plural

sacra

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 /

plural

sacra

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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Etymology

Origin of sacrum

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

Compare meaning

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

• sacrum vs. coccyx

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

Lonely Island member Jorma Taccone shattered his pelvis and detached his sacrum after a recent fall from a 20-foot ladder at his farmhouse in Connecticut.

From Los Angeles Times • Sep. 4, 2025

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

From Seattle Times • May 15, 2024

She curls into a ball, pounding her fists against the floor, and later balances on her sacrum, torso gently circling, in a resemblance of yearning or prayer.

From New York Times • Dec. 11, 2022

Intervertebral discs composed of fibrous cartilage lie between adjacent vertebral bodies from the second cervical vertebra to the sacrum.

From Textbooks • Jun. 9, 2022

Position: Sitting with legs crossed; pain in and about right knee; stretching arm; tensive drawing from left shoulder up to neck; lifting; tensive drawing in left shoulder; pain in sacrum.

From New, Old, and Forgotten Remedies: Papers by Many Writers by Anshutz, Edward Pollock

Related Words

• backside