syzygy

The story

1. Ancient Greek · derived fromσυζυγία“a union, a yoke, a pair”
2. Late Latin · borrowed fromsȳzygia“a conjunction”
3. English todaysyzygy

From Late Latin sȳzygia (“a conjunction”), from Ancient Greek συζυγία (suzugía, “a union, a yoke, a pair”). This word was recognized as English in 1847 (in its astronomical meaning).