urosacral

from The Century Dictionary.

• Situated between the sacrum and the coccyx; of or pertaining both to the sacrum and to the coccyx: as, the urosacral region.
• noun In ornithology, any vertebra of the urosacral region; any vertebra between the last true sacral and the first free caudal. See cuts under sacrarium and sacrum.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Anat.) Of or pertaining to both the caudal and sacral parts of the vertebral column.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective anatomy Of or pertaining to both caudal and sacral parts of the vertebral column.