Per Jim Berkland: The word, SYZYGY, is in your dictionary, surprisingly enough. It refers to an alignment of celestial bodies, primarily the Sun, Moon, and Earth, and it happens twice a month at the time of a new or full Moon. At such times, the gravitational forces are in line, and the ocean tides (as well as the solid Earth tides) are at a maximum, especially if the bodies are close together. The Earth and Moon are closest (at perigee) once a month; the Earth and Sun are closest (perihelion) once a year in early January. Thus the most extreme gravitational stress on the Earth's crust and oceans must occur in early January, if a syzygy and perigee occur on the same day. The optimum such example in 600 years was on January 4, 1912, when syzygy and perigee were only six minutes apart. On that day the strongest quake (5.5M) in California/Nevada in two years occurred near Bishop, California.

Dictionary the word SYZYGY.

Main Entry: syz·y·gy
Pronunciation: 'si-z&-jE
Function: noun
Inflected Form(s): plural -gies
Etymology: Late Latin syzygia conjunction, from Greek, from syzygos yoked together, from syn- + zygon yoke -- more at YOKE
: the nearly straight-line configuration of three celestial bodies (as the sun, moon, and earth during a solar or lunar eclipse) in a gravitational system