"conjunction or opposition of a heavenly body with the sun," 1650s, from Late Latin syzygia, from Greek syzygia "yoke, pair, union of two, conjunction," from syzygein "to yoke together," from syn- "together" (see syn-) + zygon "yoke" (see jugular).
Either of two points in the orbit of a celestial body where the body is in opposition to or in conjunction with the Sun.
Either of the two points in the orbit of the Moon when it lies in a straight line with the Sun and Earth. A new moon syzygy occurs when the Moon is between the Sun and the Earth; a full moon syzygy occurs when the Earth is between the Moon and the Sun.
The configuration of the Sun, Moon, and Earth when lying in a straight line.