noun. A small triangular bone at the base of the spinal column in humans and other apes, consisting of several fused rudimentary vertebrae.

noun. In human anatomy, the part of the spinal column consisting of the last four bones, the caudal vertebræ or tail-bones, which are stunted and usually ankylosed together. See cut under skeleton.

noun. In comparative anatomy and zoology, the caudal vertebræ, when few and small, or ankylosed together; the bony tail itself, when short, as in a bird.

noun. The end of the vertebral column beyond the sacrum in man and tailless monkeys. It is composed of several vertebræ more or less consolidated.

noun. The final fused vertebrae at the base of the spine.

noun. the end of the vertebral column in humans and tailless apes

"The sore coccyx is a result of sitting down for too long, in the same position, in a half decent chair!"