trigon

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A triangular lyre or harp of Roman and Greek antiquity.
2. n. See triplicity.
3. n. Archaic A triangle.

Century Dictionary and Cyclopedia

1. n. The prominent anterior portion of an upper molar tooth forming a triangular area at whose angles are the three principal cusps —the protocone, paracone, and metacone. The study of the Mesozoic mammals has left no doubt that the upper and lower triangles, or ‘trigon’ and ‘trigonid,’ were derived from the reptilian protocone by the addition of lateral cusps. See cut under tooth, 1.
2. n. An abbreviation of trigonometrical; of trigonometry.
3. n. A triangle.
4. n. In astrology: The junction of three signs, the zodiac being divided into four trigons: the watery trigon, which includes Cancer, Scorpio, and Pisces; the earthly trigon, Taurus, Virgo, and Capricornus; the airy trigon, Gemini, Libra, and Aquarius; and the fiery trigon, Aries, Leo, and Sagittarius.
5. n. Trine: an aspect of two planets distant 120 degrees from each other.
6. n. In antiquity: A kind of triangular lyre or harp. Also called trigonon.
7. n. A game at ball played by three persons standing so as to be at the angles of a triangle.
8. n. An instrument of a triangular form, used in dialing.
9. n. In conchology, a shell of the genus Trigonia.
10. n. A trig; a skid.

Wiktionary

1. n. geometry, rare A triangle.
2. n. An ancient triangular harp of Oriental origin which had four strings and was often used for banquet music. Also called sabbeka, sackbut, sambuca.
3. n. astrology A division consisting of three signs.
4. n. astrology A trine; an aspect of two planets distant 120 degrees from each other.
5. n. An old ball game played by three people standing in a triangular formation.

GNU Webster's 1913

1. n. A figure having three angles; a triangle.
2. n. A division consisting of three signs.
3. n. Trine, an aspect of two planets distant 120 degrees from each other.
4. n. A kind of triangular lyre or harp.
5. n. A kind of game at ball played by three persons standing at the angular points of a triangle.
6. n. (Zoöl.) The cutting region of the crown of an upper molar, usually the anterior part. That of a lower molar is the Tri"go*nid (�).

WordNet 3.0

1. n. a three-sided polygon
2. n. (astrology) one of four groups of the zodiac where each group consists of three signs separated from each other by 120 degrees
3. n. a triangular lyre of ancient Greece and Rome