Ontology Outreach Advisory

In addition to its formal definition, each vocabulary (i.e. concept label) in an ontology should be described by a gloss. A gloss is an auxiliary informal description of the intended meaning (i.e. concept) for the commonsense perception of humans.

The purpose of a gloss is not to provide or catalogue general information and comments about a concept, as conventional dictionaries and encyclopedias do. A gloss, for formal ontology engineering purposes, is supposed to render factual knowledge that is critical to understanding a concept, but that is unreasonable, implausible, or very difficult to formalize and/or articulate explicitly. An ontology, in this way, will have twofold parts: its typical formal axioms (i.e. classes, relations, and rules/constraints), and informal descriptions (i.e. glosses).

What should and should not be provided in a gloss.

1. It should start with the principal/super type of the vocabulary being defined. For example, "Search engine: A computer program that ...", "Invoice: A business document that..."University: An institution of ...".
2. It should be written in the form of propositions, offering the reader inferential knowledge that helps him to construct the image of the concept. For example, instead of defining 'Search engine' as "A computer program for searching the internet", or "One of the most useful aspects of the World Wide Web. Some of the major ones are Google, Galaxy... .". One can also say "A computer program that enables users to search and retrieve documents or data from a database or from a computer network...".
3. More importantly, it should focus on distinguishing characteristics and intrinsic properties that differentiate the concept from other concepts. For example, compare the following two glosses of a 'Laptop computer': (1) "A computer that is designed to do pretty much anything a desktop computer can do. It runs for a short time (usually two to five hours) on batteries"; and (2) "A portable computer small enough to use in your lap...". Notice that according to the first gloss, a 'server computer' running on batteries can be seen as a laptop computer; also, a 'Portable computer' that is not running on batteries is not a 'Laptop computer'.
4. The use of supportive examples is strongly encouraged: (1) to clarify true cases that are commonly known to be false, or false cases that are known to be true; and (2) to strengthen and illustrate distinguishing characteristics (by using examples and counter-examples). The examples can be types and/or instances of the concept being defined. For example: "Legal Person: An entity with legal recognition in accordance with law. It has the legal capacity to represent its own interests in its own name, before a court of law, to obtain rights or obligations for itself, to impose binding obligations, or to grant privileges to others, for example as a plaintiff or as a defendant. A legal person exists wherever the law recognizes, as a matter of policy, the personality of any entity, regardless of whether it is naturally considered to be a person. Recognized associations, relief agencies, committees and companies are examples of legal persons".
5. It should be consistent with the formal axioms in the ontology. In other words, what have said in a gloss should not contradict the formal axioms, and vice versa.
6. It should be sufficient, clear, and easy to understand.