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 (dī′ăd′, -əd)
1. Two individuals or units regarded as a pair: the mother-daughter dyad.
2. Biology One pair of homologous chromosomes resulting from the division of a tetrad during meiosis.
3. Mathematics
a. A function that draws a correspondence from any vector u to the vector (v·u)w and is denoted vw, where v and w are a fixed pair of vectors and v·u is the scalar product of v and u. For example, if v = (2,3,1), w = (0,-1,4), and u = (a,b,c), then the dyad vw draws a correspondence from u to (2a + 3b + c)w.
b. A tensor formed from a vector in a vector space and a linear functional on that vector space.
Made up of two units.

[From Greek duas, duad-, from duo, two; see dwo- in Indo-European roots.]


1. (Mathematics) 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
2. (Chemistry) an atom or group that has a valency of two
3. a group of two; couple
[C17: from Late Latin dyas, from Greek duas two, a pair]


(ˈdaɪ æd)

1. a group of two; couple; pair.
2. the double chromosomes resulting from the separation of the four chromatids of a tetrad.
3. an element, atom, or group having a valence of two.
4. Math. two vectors with no symbol connecting them, usu. considered as an operator.
a. two people involved in an ongoing relationship or interaction.
b. the relationship or interaction itself.
6. of two parts; dyadic.
[1665–75; < Greek dyad-, s. of dyás pair <dý(o) two]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.dyad - two items of the same kinddyad - two items of the same kind    
fellow, mate - one of a pair; "he lost the mate to his shoe"; "one eye was blue but its fellow was brown"
2, II, two, deuce - the cardinal number that is the sum of one and one or a numeral representing this number
doubleton - (bridge) a pair of playing cards that are the only cards in their suit in the hand dealt to a player
References in periodicals archive ?
Tenders are invited for Procurement of dyad thermal cycler
The compensatory index matrix for whole groups was constructed in order to understand the compensatory like growth of each combination dyad.
The purpose of sharing instruction was to teach participants to share tokens in a dyad arrangement.
In our study we designed a semi-structured interview to collect data from each parents-child dyad together.
Increasingly popular for Lx Solutions clients are dyad and triad educational models, where physicians are paired with hospital administrators and/or clinical support staff to improve patient care and augment lines of communication.
We used intraclass correlations to assess concordance between CPs' and PwMCIs' DAS scores and compared concordance strengths between dyad types with Fisher r-to-z tests.
Interpersonal coordination was assessed using two tri-axial wireless accelerometers, one fixed to each dancer, that allowed for off-line kinematic analyses of dyad correlation, mean relative phase, and mean standard deviation of relative phase of the up--down movements of one of the hands of the two dancers.
He provides illustrations of his approach in dyads representing wicked problems--socio-cultural ones like global/local and traditional/modern, socio-ecological problems in relation to nature/culture, and socio-religious problems in relation to the spiritual/material and faith/reason--and applies it to understanding them in formal education, such as in the mind/body binary in teaching dance and the concrete/abstract dyad in teaching math.
In this study, we investigated co-learning between PSTs and CTs; operationalized as (a) building a shared language and purpose for ambitious practices, (b) sharing a repertoire of ways of reasoning with tools and routines specific to the PST-CT dyad, (c) taking principled risks together when experimenting with ambitious practices, and (d) co-developing and adopting innovative instantiations of the ambitious practices.
Through a mesmerising display of light, music and movement the Dyad Man-Machines portrayed two polarised visions of the future to "find harmony between ego and spirit".
The terms dyad, trio, and quartet hereafter refer to groups of two, three, or four full sibs, respectively.