Anat. [L. coccȳx, a. Gr. κόκκυξ, -ῡγ- cuckoo, also in Galen the os coccygis, or cuckoo bone, so called because in man it was supposed to resemble the bill of the cuckoo.] The small triangular bone appended to the point of the sacrum and forming the termination of the spinal column in man, formed by the coalescence of four rudimental coccygeal vertebræ; also, an analogous part in birds or other animals.
1615. Crooke, Body of Man, 493. In Dogs and Apes there are three coniugations proceeding out of the Coccyx or rump-bone.
1754–64. Smellie, Midwif., I. 75. The Coccyx is moveable at its connection with the Sacrum as are also the four bones that compose it.
1879. trans. De Quatrefages’ Hum. Spec., 52. In the sheep of central Asia the tail disappears and is reduced to a simple coccyx.
