/ ˈdaɪæd; NAmE / noun
1.
( technical ) something that consists of two parts :
the mother-child dyad
2.
( mathematics ) an operator which is the combination of two vectors
► dyad·ic / daɪˈædɪk; NAmE / adjective
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WORD ORIGIN
late 17th cent. (originally denoting the number two or a pair): from late Latin dyas , dyad- , from Greek duas , from duo two. Current senses date from the late 19th cent.