In 1884, Angelo Moriondo of Turin, Italy, demonstrated the first working example of an espresso machine.
four, IV, tetrad, quatern, quaternion, quaternary, quaternity, quartet, quadruplet, foursome, Little Joe
(noun) the cardinal number that is the sum of three and one
Source: WordNet® 3.1
tetrad (plural tetrads)
A group of four things.
Synonyms: foursome, quartet, Thesaurus:quartet
(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.
• monad · duad, dyad · triad · tetrad · pentad · hexad · heptad · octad · ennead, nonad · decad, decade · hendecad · dodecad, duodecade
• ratted, tarted
Source: Wiktionary
Tet"rad, n. Etym: [L. tetras, -adis, Gr. tétrade.]
1. The number four; a collection of four things; a quaternion.
2. (Chem.)
Definition: A tetravalent or quadrivalent atom or radical; as, carbon is a tetrad.
Source: Webster’s Unabridged Dictionary 1913 Edition
3 April 2025
(noun) an assemblage of parts that is regarded as a single entity; “how big is that part compared to the whole?”; “the team is a unit”
In 1884, Angelo Moriondo of Turin, Italy, demonstrated the first working example of an espresso machine.