tetrad

[te-trad]

SEE MORE SYNONYMS FOR tetrad ON THESAURUS.COM

noun

a group of four.

the number four.

Cell Biology. a group of four chromatids formed by synapsis at the beginning of meiosis.

Chemistry. a tetravalent or quadrivalent element, atom, or group.

Origin of tetrad

1645–55; < Greek tetrad- (stem of tetrás) group of four

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for tetrad

quadruplicate, quadruple, tetrad, quaternary, tetralogy, quaternity, quadrivium, quadruplet, quaternion, quadrumvirate, quartet, quadrigeminal, quadripartite, quadrivial, quaternate

Examples from the Web for tetrad

Historical Examples of tetrad

The tetrad for the perfect figure—the cube, length, depth, and width.
Notes and Queries for Worcestershire
John Noake
Having sent for that Brhman, he learnt from him a tetrad of gths.
The Gtakaml
rya Sra
They are aborting members of the tetrad, and appear to have been used as food by the other spores.
Ancient Plants
Marie C. Stopes
Such an axis of symmetry is known as a tetrad axis of symmetry.
Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7
Various
If the second cell division plane is formed at right angles to the first, a cell surface or tetrad is formed.
Outlines of Dairy Bacteriology, 8th edition
H. L. Russell

British Dictionary definitions for tetrad

tetrad

noun

a group or series of four

the number four

botany a group of four cells formed by meiosis from one diploid cell

genetics a four-stranded structure, formed during the pachytene stage of meiosis, consisting of paired homologous chromosomes that have each divided into two chromatids

chem an element, atom, group, or ion with a valency of four

ecology a square of 2 × 2 km used in distribution mapping

Word Origin for tetrad

C17: from Greek tetras, from tettares four

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

Word Origin and History for tetrad

1650s, from Greek tetras (comb. form tetrad-) "group of four" (see tetra-).

tetrad in Medicine

tetrad

[tĕt′răd′]

n.

A group or set of four.

A tetravalent atom, radical, or element.

A group of four chromatids formed from each of a pair of homologous chromosomes that split longitudinally during the prophase of meiosis.

tetrad in Science

tetrad

[tĕt′răd′]

A four-part structure that forms during prophase I of meiosis and consists of two homologous chromosomes, each composed of two identical chromatids. During prophase I of meiosis, one chromosome exchanges corresponding segments of genetic material with the other chromosome in the tetrad in the process called crossing over. See more at meiosis.

A group of four cells, as of spores or pollen grains, formed from a parent cell by meiosis. As part of the process of spermatogenesis, a spermatocyte divides into a tetrad of four spermatids, cells which go on to develop into sperm. See more at spermatogenesis.