coccyx

American  

[kok-siks] / ˈkɒk sɪks /

noun

plural

coccyges

1. a small triangular bone forming the lower extremity of the spinal column in humans, consisting of four ankylosed rudimentary vertebrae.

2. a corresponding part in certain animals.

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coccyx British  

/ kɒkˈsɪdʒɪəl, ˈkɒksɪks /

noun

1. a small triangular bone at the end of the spinal column in man and some apes, representing a vestigial tail

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coccyx Scientific  

/ kŏk′sĭks /

plural

coccyges

1. A small triangular bone at the base of the spine in humans and apes. It is composed of several fused vertebrae.

2. Also called tailbone

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Other Word Forms

• coccygeal adjective
• intercoccygeal adjective
• precoccygeal adjective

Etymology

Origin of coccyx

1605–15; < New Latin < Greek kókkyx cuckoo, from its resemblance to a cuckoo's beak

Compare meaning

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

• sacrum vs. coccyx

Example Sentences

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 pelvic diaphragm, spanning anteriorly to posteriorly from the pubis to the coccyx, comprises the levator ani and the ischiococcygeus.

From Textbooks • Jun. 19, 2013

Figure 7.20 Vertebral Column The adult vertebral column consists of 24 vertebrae, plus the sacrum and coccyx.

From Textbooks • Jun. 19, 2013

Congenital Sacro-coccygeal Tumours—Teratoma.—Many varieties of congenital tumours are met with in the region of the sacrum and coccyx.

From Manual of Surgery Volume Second: Extremities—Head—Neck. Sixth Edition. by Miles, Alexander