[dy.ad] n [LL dyad-, dyas, fr. Gk, fr. dyo] (1675) 1: pair; specif: two individuals (as husband and wife) maintaining a sociologically significant relationship
2: a meiotic chromosome after separation of the two homologous members of a tetrad
3: a mathematical operator indicated by writing the symbols of two vectors without a dot or cross between (as AB) -- dy.ad.ic adj -- dy.ad.i.cal.ly adv