Nor-

{
  "id": "MLC-T-CHM-008064",
  "term": "Nor-",
  "field": "Chemistry",
  "definition": "A prefix in chemical nomenclature indicating the elimination of one or more carbon atoms, along with their attached hydrogens, from a parent structure. The use of 'nor-' signifies the unbranched analogue of a branched parent compound or the removal of a methylene group from a ring system, leading to ring contraction. For example, norbornane is derived from the parent structure bornane by the removal of three methyl groups, and noradrenaline lacks the N-methyl group present in adrenaline.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "elimination",
    "branch"
  ],
  "references": [
    "Blue Book, p. 497 (https://www.acdlabs.com/iupac/nomenclature/)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/nor/"
}