tetrad

Etymology
From, analysable as.

Noun

 * 1) A group of four things.
 * 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)  A group of four haploid and immature pollen grains in tetrahedral fashion produced by meiotic microsporogenesis.
 * 4)  A unit of land area of two by two (that is, four) square kilometres.
 * 5)  A tetravalent atom or radical.
 * 6)  A group of four basis vectors for a four-dimensional manifold in differential geometry.
 * 7)  A chord comprised of four notes; a tetrachord.
 * 1)  A tetravalent atom or radical.
 * 2)  A group of four basis vectors for a four-dimensional manifold in differential geometry.
 * 3)  A chord comprised of four notes; a tetrachord.

Translations

 * Bulgarian:
 * Finnish: tetradi, bivalentti
 * French:
 * German:
 * Greek:
 * Ido:
 * Italian:
 * Russian:
 * Spanish: tétrada