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)



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