Diads

Diads (also spelled dyads in some fields) describe a unit composed of two related elements. The term is used across disciplines to denote a pair that functions as a single entity within a larger system. The exact interpretation of the two elements and their relationship depends on the context.

In music theory, a diad is a two-note unit, typically considered a two-note interval or a two-note chord formed without a third. Diads are contrasted with triads and larger chords and are used to analyze harmony, voice leading, and texture. Examples include two simultaneous pitches forming a major or minor interval.

In biology and genetics, diad (often written dyad) refers to a paired set of chromosomal units. Depending on the stage and field, it can denote a pair of homologous chromosomes during meiosis or a pair of sister chromatids after DNA replication. The concept emphasizes pairing, alignment, and the subsequent separation of units during cell division.

In the social sciences, a diad is a dyadic unit describing a relationship or interaction between two individuals or groups. Diadic analysis examines how two agents influence each other, focusing on reciprocity, communication patterns, and the dynamics of two-person encounters.

Other uses exist where diad appears in terminology to indicate two connected parts or partners, such as in anthropology, psychology, or chemistry. Because the meaning shifts by field, clarification from context is typical when encountering the term diad or dyad.