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.-the coupling together of different feet; as, in greek verse, an iambic syzygy.-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.-the immovable union of two joints of a crinoidal arm.