|1.||maths an operator that is the unspecified product of two vectors. It can operate on a vector to produce either a scalar or vector product|
|2.||an atom or group that has a valency of two|
|3.||a group of two; couple|
|[C17: from Late Latin dyas, from Greek duas two, a pair]|
dyad dy·ad (dī'ād', -əd)
Two individuals or units regarded as a pair, such as a mother and a daughter.
A divalent atom or radical.
One pair of homologous chromosomes resulting from the division of a tetrad during meiosis.