Quadro-

{
  "id": "MLC-T-CHM-009721",
  "term": "Quadro-",
  "field": "Chemistry",
  "definition": "A prefix in inorganic cluster nomenclature showing that four atoms are bonded into a quadrangle, such as a square. It belongs to the set of geometry descriptors that includes triangulo for three atoms in a triangle and tetrahedro for four atoms in a tetrahedron. It is not a multiplying prefix, unlike the tetra- in a tetradentate ligand name.",
  "subject": "Organic and Biomolecular Chemistry",
  "references": [
    "Blue Book, p. 465 (https://www.acdlabs.com/iupac/nomenclature/)",
    "Red Book, 3rd ed., p. 245"
  ],
  "url": "https://mlchart.com/terminology/chemistry/quadro/"
}