from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A bone of the wrist in the proximal row of carpal bones.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The triquetral bone
- n. An astronomical instrument.
from the GNU version of the Collaborative International Dictionary of English
- n. One of the bones of the carpus; the cuneiform. See cuneiform (b).
from The Century Dictionary and Cyclopedia
- n. An instrument used by ancient and medieval astronomers for measuring altitudes of heavenly bodies; the parallactic rules of Ptolemy. It consisted of three rods: one vertical, the second jointed to it at the top and carrying sights, the third jointed to the first at the bottom. The second and third were graduated.
- n. In anatomy, one of the irregular, often triangular, Wormian bones found in the lambdoid suture of the skull: more fully called os triquetrum, and generally in the plural ossa triquetra.
Latin, neuter of triquetrus, three-cornered; see triquetrous.(American Heritage® Dictionary of the English Language, Fourth Edition)