I get a daily email from Word Genius called word of the day. Feeds you odd words. Today's word was syzygy.
A greek word from the 17th century, Syzygy has two meanings. In a physical, cosmological sense it is the straight alignment of three heavenly bodies as in an eclipse. In a human, interactional sense it describes a situation where two people, ideas or events are confluent or in alignment, either alike or in opposition.
I was not familiar with the term but I find it curious, etymologically speaking. Because rarely would a word be binary in one meaning and ternary or trinary in another. Wonder how that happened?
I looked it up, hoping to find further information.
And I find a different binary meaning in biology, Syzygy, the pairing of chromosomes during meiosis.
Syzygy comes from the greek word syzygos which derives from syn (together) and zygon (to yoke).
I found another astronomical definition of the word that relates to two rather than three - Either of two points in the orbit of a celestial body where the body is in opposition to or in conjunction with the Sun.
I may never figure this one out.