Syzygy

noun, plural syzygies.
1.
Astronomy. an alignment of three celestial objects, as the sun, the earth, and either the moon or a planet:
Syzygy in the sun-earth-moon system occurs at the time of full moon and new moon.
2.
Classical Prosody. a group or combination of two feet, sometimes restricted to a combination of two feet of different kinds.
3.
any two related things, either alike or opposite.
noun (pl) -gies
1.
either of the two positions (conjunction or opposition) of a celestial body when sun, earth, and the body lie in a straight line: the moon is at syzygy when full
2.
(in classical prosody) a metrical unit of two feet
3.
(rare) any pair, usually of opposites
4.
(biology) the aggregation in a mass of certain protozoans, esp when occurring before sexual reproduction

syzygy syz·y·gy (sĭz’ə-jē)
n.

The association of gregarine protozoa end-to-end or in lateral pairing without sexual fusion.

The pairing of chromosomes in meiosis.

sy·zyg’i·al (sĭ-zĭj’ē-əl) adj.
syzygy
(sĭz’ə-jē)

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.