Tetrad

//ˈtɛtɹæd// noun

noun ·Uncommon ·Advanced level

Definitions

Noun
  1. 1
    A group of four things.

    "Religious movements and cults are often founded on a tetrad of elements: a prophet, a prophecy, a book, and a revelation."

  2. 2
    the cardinal number that is the sum of three and one wordnet
  3. 3
    Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.
  4. 4
    A group of four haploid and immature pollen grains in tetrahedral fashion produced by meiotic microsporogenesis.
  5. 5
    A unit of land area of two by two (that is, four) square kilometres.

    "They took figures for the abundance of invasive weeds mapped according to the normal grid unit of the 'hectad', or 10 × 10 km square, and then looked at how abundant these species were mapped at a much finer scale – in 'tetrads', or 2 × 2 km squares, inside these hectads."

Show 3 more definitions
  1. 6
    A tetravalent atom or radical.
  2. 7
    A group of four basis vectors for a four-dimensional manifold in differential geometry.
  3. 8
    A chord comprised of four notes; a tetrachord.

Example

More examples

"Religious movements and cults are often founded on a tetrad of elements: a prophet, a prophecy, a book, and a revelation."

Etymology

From Ancient Greek τετράς (tetrás), analysable as tetra- + -ad.

Related phrases

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.