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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.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


relating to something that has a group of four
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
Wayne Constantineau and Eric McLuhan's Human Equation describes a tetradic instrument that offers insights into how the four pillars described in the Action Plan interact.
We now have new, and prominently-located, Administrative and Admissions Buildings; an Early Childhood Education Center and preschool; a new Student Center that contains, among other things, a nice fitness room; a very new Fine Arts building with a sweeping glass front; and, last but not least, dorms whose tetradic structure forms quads, with one of those quads being anchored on one end by a new Science building, which also helped create a larger, central quad on which students throw Frisbees to bandanna-wearing dogs when the weather gets warm.
He modified Abrams's poetical triangle into a "tetradic circle" that is around four elements: world, writer, works, and readers derived from the Abram's four elements and shows an affinity with traditional Chinese poetics (see also Huang and Tong).
Powers, The Global Village: Transformations in World Life and Media in the 21st Century (New York: Oxford University Press, 1992): see the tetradic glossary, pp.
The logic of coalition formation could be further applied on a tetradic level, for example with two allied suppliers interacting with two allied buyers.
(14) Teresa Soufas states that, "The roots of humoral theory itself can be traced to Pythagorean philosophy and its insistence upon tetradic categories of time and natural elements" (5).
1979; Long 1916; Viveiros de Castro 1998; but see also Allen's 'tetradic' model in 1986, 1998).