tetrad
[noun]
Synonyms: quartet, four, foursome, quartetto, quaternion, quatuor

[TahlilGaran] English Synonym Dictionary ▲

tetrad noun. ['tɛtrad] M17.
[Greek tetrad-, tetras a group of four, the number four: see -AD¹.]
1. A sum, group, or set of four. M17.
■ A. Stevens A tetrad of distinct elementsearth, air, fire and water.

2. Chemistry. Orig., a tetravalent element or group. Now, a tetrameric unit within a polymer. M19.

3. Biology. A group of four cells, spores, pollen-grains, etc. Also, a group of four homologous chromatids formed during meiotic division. L19.

4. A square block of four 1-kilometre squares within a 10-kilometre square, used as a unit in biological recording. M20.

■ te'tradic adjective of, pertaining to, or of the nature of a tetrad; spec. (Chemistry, now rare or obsolete) tetravalent L18.

■ Tetradite noun (Ecclesiastical History) a worshipper of a tetrad, esp. one who believes that there are four persons in the Godhead E18.

[TahlilGaran] English Dictionary ▲