Ontology classes and labels

A class in an ontology is similar to a class in a taxonomy, but with a few differences.

In this article:

  • What are non-taxonomic classes?
  • What is an individual?
  • Creating an ontology class

Non-taxonomic classes​

Ontologies are organised by hierarchising the classes of objects or concepts from the broadest to the narrowest.

For example, in a e-commerce ontology, the Clothing class contains in particular the Dresses class and the Pants class, which contains Jeans class. Jeans are a kind of pants that are a kind of clothing.

But we may want to create classes that group together things that do not have the same nature but have another point in common: these are the non-taxonomic classes.

For example, in the e-commerce ontology, the Skiing class includes sub-classes of products related to skiing: Skiing poles, Skiing boots, Skiing suits, Ski covers, etc. All these products relate to skiing but are not kinds of skiing.

For an optimal use of the Lettria ontology, it is preferable to avoid as much as possible the use of these non-taxonomic classes.

But if you use them, it is important to distinguish them from other classes, because it has consequences for the ontology.

In this case, it must be indicated by checking the ‘Non-taxonomic class’ box.


An individual is a single element (person, object, idea...) belonging to a class.


In an ontology of artistic works, Matrix is an individual belonging to the class Movie.

In a geographic ontology, Italy is an individual belonging to the class Country.

Creating an ontology class

  1. Click on the Create icon (+)
  2. Type your class name. By default, the class name will also be the preferred label. You can edit it later if needed.
  3. Click on Create. It will create a narrower class related to the parent class.

If you need more help, please reach out to us at hello@lettria.com