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Sacro- is a combining form used like a prefix representing sacrum. The sacrum is a bone in the lower back made up of fused vertebrae and forming part of the pelvis. Sacro- is used in medical and scientific terms, especially in anatomy.

Sacro- ultimately comes from the Latin phrase os sacrum, meaning “holy bone.” Os means “bone” (see our 51�Թ�s That Use osteo- article) and sacrum means “holy.” The Latin word sacrum is related to the English word sacred as well as sacrament and sacrosanct. Why this bone was originally thought to be “holy” is much disputed.

What are variants of sacro-?

When combined with words or word elements that begin with a vowel, sacro- becomes sacr-, as in sacralgia.

One term in anatomy that features the combining form sacro- is sacrococcygeal, meaning “of, relating to, or affecting the sacrum and coccyx.”

Sacrococcygeal is indeed an intimidating-looking word, but we can put our knowledge of root words to use and break it down. As we’ve seen, sacro- refers to the sacrum. The second part of the word, -coccygeal is from the adjective form of coccyx. The coccyx is a bone at the bottom of the spine below the sacrum, commonly known as the tailbone. So, sacrococcygeal concerns the sacrum and coccyx bones in the body.

What are some words that use the combining form sacro-?

• sacroanterior position
• sacroiliac
• sacrolumbar
• sacroposterior position
• sacrospinal
• sacrosciatic
• sacrovertebral

What are some other forms that sacro- may be commonly confused with?

• saccharo-
• sarco-

The sacrovertebral is an adjective concerning what two parts of the body?