nominal property

https://doi.org/10.1351/goldbook.09979

Property of a phenomenon, body, or substance, where the property has no size.

Examples:
  1. Colour at a specified lighting of a given leaf of a plant.
  2. Sequence variation of nucleotides of a given gene.
  3. Taxon of a bacterium in a given sample of urine.
  4. Shape of the nucleus of a given white blood cell.
Notes:
  1. The concept "nominal property" is defined as the opposite of "quantity", i.e. the former concept lacks the essential characteristic of "size" (or "magnitude"). In such cases, ISO 704:2009-6.5.4 allows a "negative definition".
  2. The term "attribute" has sometimes been used to designate "nominal property", but not here.
  3. The term "qualitative property" is also used, but not here as it is ambiguous because "ordinal quantity" is often included under that term.
  4. "Nominal property" is sometimes termed "nameable property", but not here.
Source:
PAC, 2018, 90, 913. 'Vocabulary on nominal property, examination, and related concepts for clinical laboratory sciences (IFCC-IUPAC Recommendations 2017)' on page 915 (https://doi.org/10.1515/pac-2011-0613)