tetrad

IPA: tˈɛtræd

A group of four things.
(biology) Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.
(biology) A group of four haploid and immature pollen grains in tetrahedral fashion produced by meiotic microsporogenesis.
(cartography) A unit of land area of two by two (that is, four) square kilometres.
(chemistry) A tetravalent atom or radical.
(mathematics) A group of four basis vectors for a four-dimensional manifold in differential geometry.

Examples of "tetrad" in Sentences

Incidentally, Radix is actually the first book in a thematic “tetrad”.
You can generate single monochromatic, complimentary, triad, tetrad, analogic and accented analogic colour palettes.
Beyond the 1980's: Space defense, laser weapons, and the strategic tetrad (Hudson Institute paper) by Barry Smernoff
Religious movements and cults are often founded on a tetrad of elements: a prophet, a prophecy, a book, and a revelation.
To create a tetrad, and discover insights into any human technology whatsoever, consider any artifact, and ponder these questions:
The color palette is actually pretty consistent with typical color scheme design methods looks sort of like a color tetrad was made once they settled on the precise shade of yellow.
(I, Thou, objective world) to a tetrad, by a process of completion, as it were, to embrace the “godhead that lives in impenetrable silence”, the objective counterpart of the Ego, which had been suggested to him by his readings of Eckhart.
In the commencement of these it is very difficult to determine those which will come to a crisis after a long interval; for these beginnings are very similar, but one should pay attention from the first day, and observe further at every additional tetrad, and then one cannot miss seeing how the disease will terminate.