English
dyadic
From dyad + -ic.
Formed from dyad + -ic
Proto-Indo-European *duwó
Proto-Hellenic *dúwo
Ancient Greek δύο ‘two’
Ancient Greek δυάς ‘a group of two’
English dyad
The story
The mathematics sense was coined by American scientist Josiah Willard Gibbs in 1884 in the second half of his book Elements of Vector Analysis.
Today it means
adj having an arity of two (taking two arguments or operands)
Language periods are conventional ranges, not dates for this word.
Etymograph / dyadic