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1. A group or set of four.
2. A tetravalent atom, radical, or element.
3. Biology
a. A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.
b. A group of four haploid cells, such as spores, formed by meiotic division of one mother cell.

[Greek tetras, tetrad-; see kwetwer- in Indo-European roots.]

te·trad′ic adj.


1. (Mathematics) a group or series of four
2. (Mathematics) the number four
3. (Biology) botany a group of four cells formed by meiosis from one diploid cell
4. (Genetics) genetics a four-stranded structure, formed during the pachytene stage of meiosis, consisting of paired homologous chromosomes that have each divided into two chromatids
5. (Chemistry) chem an element, atom, group, or ion with a valency of four
6. (Environmental Science) ecology a square of 2 × 2 km used in distribution mapping
[C17: from Greek tetras, from tettares four]


(ˈtɛ træd)

1. a group of four.
2. the number four.
3. Biol. a group of four chromatids formed by synapsis at the beginning of meiosis.
[1645–55; < Greek tetrad-, s. of tetrás group of four]


 a group of four; four things regarded together as a single object or thought.
Example: Great Tetrad of senior wranglers, 1898.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.tetrad - the cardinal number that is the sum of three and onetetrad - the cardinal number that is the sum of three and one
digit, figure - one of the elements that collectively form a system of numeration; "0 and 1 are digits"


n. tétrada, grupo de cuatro elementos similares.