Definitions of syzygy

1. The point of an orbit, as of the moon or a planet, at which it is in conjunction or opposition; -- commonly used in the plural.

2. The coupling together of different feet; as, in Greek verse, an iambic syzygy.

3. Any one of the segments of an arm of a crinoid composed of two joints so closely united that the line of union is obliterated on the outer, though visible on the inner, side.

4. The immovable union of two joints of a crinoidal arm.

5. The conjunction or opposition of a planet with the sun, or of any two of the heavenly bodies; the period of new or full moon, when the sun, moon, and earth are in one line.

6. The point at which the moon or a planet in its orbit is in conjunction or opposition with the sun; the times of both new and full moon.

7. A close suture of two adjacent arms, found in Crinoids; a number of individuals, two to five, adhering to one another in strings in the association of Gregarines.