I. noun
also di·ad ˈdīˌad, -īəd
( -s )
Etymology: Late Latin dyad-, dyas two (n.), from Greek, from dyo two — more at two
1. : two units treated as one : couple , pair ; specifically : a pair of individuals (as husband and wife, teacher and pupil) maintaining a sociologically significant relationship
2. : a bivalent element, atom, or radical
3. : a meiotic chromosome after separation of the two homologous members of a tetrad
4. mathematics : an operator indicated by writing the symbols of two vectors without a dot or cross between (as AB)
II.
variant of diad