[ dahy-ad ]
/ ˈdaɪ æd /
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a group of two; couple; pair.
  1. a secondary morphological unit, consisting of two monads: a chromosome dyad.
  2. the double chromosomes resulting from the separation of the four chromatids of a tetrad.
Chemistry. an element, atom, or group having a valence of two.Compare monad, triad (def. 2a).
Mathematics. two vectors with no symbol connecting them, usually considered as an operator.
  1. two persons involved in an ongoing relationship or interaction.
  2. the relationship or interaction itself.


of two parts; dyadic.



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Sometimes di·ad .

Origin of dyad

First recorded in 1665–75; from Greek dyad- (stem of dyás ) “pair,” equivalent to dý(o) “two” + -ad- noun suffix; see origin at two, -ad1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for dyad

/ (ˈdaɪæd) /


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
an atom or group that has a valency of two
a group of two; couple
C17: from Late Latin dyas, from Greek duas two, a pair
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for dyad

[ dīăd′, -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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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