Syzygy occurs when the moon (or a planet) is in opposition or conjuction with the Earth and Sun; the three bodies are positioned in a straight line. At syzygy, the moon (or planet) is seen as new or full (from Earth).

The points in the moon's orbit about the earth at which the moon is new or full. Glossary T

Occurs twice a month, when the Sun and the Moon are in conjunction (lined up on the same side of Earth at the new Moon) and when they are in opposition (on opposite sides of Earth at the full Moon, though usually not so directly in line as to produce an eclipse). In either case, the gravitational effects of the Sun and the Moon reinforce each other, and tidal range is increased.

the straight line configuration of 3 celestial bodies (as the sun and earth and moon) in a gravitational system

The alignment of any three celestial bodies. Planets are at syzygy when they are at opposition or conjunction (aligned with Sun and Earth).

The two points in the moon's orbit when the moon is in conjunction or opposition to the sun relative to the earth; time of new moon or full moon in the cycle of phases.

The nearly straight line configuration of three celestial.

The points in the moon's orbit about the earth at which the moon is new or full. Absolute humidity..., Backing..., Calm..., Daily mean..., Earthlight..., Fahrenheit temperature scale..., Gale..., Haboob..., Ice..., Jet streak..., Katabatic wind..., Lake effect snow..., Mackerel sky..., Nadir..., Obscuration..., Palmer drought index..., Quantitative precipitation forecast..., Radar..., Saffir..., Teleconnections..., Ultraviolet..., Valley breeze..., Walker circulation..., X-rays..., Year..., Zodiac....

Syzygy is a kind of unity, especially through coordination or alignment, most commonly used in the astronomical and/or astrological sense http://dictionary.reference.com/search?q=Syzygy&x=56&y=22.