tetrad

[te-trad]

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.

Nearby words

  1. tetracrotic,
  2. tetracyclic,
  3. tetracyclic antidepressant,
  4. tetracycline,
  5. tetracyn,
  6. tetradactyl,
  7. tetradactylous,
  8. tetradrachma,
  9. tetradymite,
  10. tetradynamous

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

Examples from the Web for tetrad


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

tetrad

n.

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

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for tetrad

tetrad

[tĕtrăd′]

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.

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

Science definitions for tetrad

tetrad

[tĕtrăd′]

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.