from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A group or set of four.
- n. A tetravalent atom, radical, or element.
- n. Biology A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.
- n. Botany Biology A group of four cells, as of spores or pollen grains, formed by division of one mother cell.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A group of four things.
- n. A tetravalent atom or radical.
- n. Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.
- n. Group of four haploid and immature pollen grains in tetrahedral fashion produced by meiotic microsporogenesis.
from the GNU version of the Collaborative International Dictionary of English
- n. The number four; a collection of four things; a quaternion.
- n. A tetravalent or quadrivalent atom or radical.
from The Century Dictionary and Cyclopedia
- n. In cytology, a group of four chromosomes formed by the division of a single chromosome; a quadripartite chromosome.
- n. The number four; also, a collection of four things. Also quadrad.
- n. In chem., an atom the equivalence of which is four, or an element one atom of which is equivalent, in saturating power, to four atoms of hydrogen.
- n. In morphology, a quaternary unit of organization resulting from individuation or integration of an aggregate of triads. See triad, dyad.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the cardinal number that is the sum of three and one
Greek tetras, tetrad-.(American Heritage® Dictionary of the English Language, Fourth Edition)