Defining and using terms | Tarantool

Defining and using terms

Defining and using terms

To write well about some subject matter, one needs to know the objects of this subject matter and use the right, carefully selected words for them. Such objects are called concepts, and the words for them are called terms.


The concept is the idea of some object, attribute, or action. It is independent of languages, audience, and products. It just exists.

For example, a large database can be partitioned into smaller instances, which are easier to operate and can exceed the throughput of a single large database instance. Such instances can exchange data for keeping it consistent between them.


The term is a word, which authors or a particular book, article, or documentation set have explicitly selected to denote a concept in a particular language and for a particular audience.

For example, in Tarantool, we use the term “[database] sharding” to denote the concept mentioned in the previous example.

The purpose of using terms is to write concisely and unambiguously, which is good for readers. But selecting terms is hard. Often there are two or more terms for one concept popular with the community, so there’s no obvious choice. Indeed, selecting and consistently using any of them is much better than not selecting and just using random terms each time. This is why it’s also helpful to restrict the usage of some terms explicitly.

restricted term

A restricted term is a word that authors have explicitly forbidden to use for denoting a concept. Such a word is sometimes used as a term for the same concept elsewhere: in the community, in other books, or other products’ documentation. Sometimes, this word is used to denote a similar but different concept. In this case, the right choice of terms helps us differentiate between concepts.

For example, in Tarantool, we don’t use the term “[database] segmentation” to denote what we call “database sharding.” Although, other authors could do so. Also, there is a term “[database] partitioning” that we use to denote a wider concept, which includes sharding and other things.

Define the term by explaining the concept. For the most important concepts and the ones unique to Tarantool, the definition should always be in our documentation.

Define each term in the document which is most relevant to it. There’s no need to gather all definitions on a particular “Glossary” page.

To define a term, use the glossary directive in the following way:

..  glossary::

        definition text

        definition text

There can be several glossary directives in a Sphinx documentation project and even in a single document. This page has two of them, for example.

The Sphinx documentation has an extensive glossary, which we can use as a reference.

When you use a term for the first time in a document, introduce it by giving a definition, synonyms, translation, examples, and links. It will help readers learn the term and understand the concept behind it.

  1. Define the term or give a link to the definition.

    Database sharding is a type of horizontal partitioning.

    To give a link to the definition, use the term role:

    For example, this is a link to the definition of :term:`concept`.
    As with any rST role, it can have :term:`custom text <concept>`.

    The resulting output will look like this:

    For example, this is a link to the definition of concept. As with any rST role, it can have custom text.

    With acronyms, you can also use the abbr role:

    Delete the corresponding :abbr:`PVC (persistent volume claim)`...

    It produces a tooltip link: PVC.

  2. Provide synonyms, including the restricted terms. Only do it on the first entry of a term.

    Database sharding (also known as …) is a type of…

  3. When writing in Russian, it’s good to add the corresponding English term. Readers may be more familiar with it or can use it in search.

    Шардирование (сегментирование, sharding) — это…

  4. Give examples or links to extra reading where you can.