tetrads

/T EH1 T R AE0 D Z/
noun
  1. 1

    A group of four things.

  2. 2

    Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.

  3. 3

    A group of four haploid and immature pollen grains in tetrahedral fashion produced by meiotic microsporogenesis.

  4. 4

    A unit of land area of two by two (that is, four) square kilometres.

  5. 5

    A tetravalent atom or radical.

  6. 6

    A group of four basis vectors for a four-dimensional manifold in differential geometry.

Source: https://en.wiktionary.org/wiki/tetrad, https://en.wiktionary.org/wiki/tetrads