Dyad (sociology)
Sociology defines dyad (from Greek dýo, "two" or Sanskrit "Dayadaha") as a group of two people, the smallest possible social group. As an adjective, "dyadic" describes their interaction.
The pair of individuals in a dyad can be linked via romantic interest, family relation, interests, work, partners in crime, and so on. The relation can be based on equality, but may be based on an asymmetrical or hierarchical relationship (master-servant).