What is a Glossary? And How to Know if Your Book Needs One

When you’re assembling the final manuscript for a book, there can be a lot of moving parts to keep track of. Everything from the introduction to index comes together to shape the way the reader experiences your work. But one element that doesn’t get talked about very often is the glossary—a useful reference section you’ll sometimes see tucked into the back pages of a nonfiction book or novel.

We’ll break down everything you need to know about glossaries, and whether or not you should include one in your own book, in this handy guide.

If you use only a few unusual words, a glossary probably isn’t necessary. But if there are quite a lot of unfamiliar terms that the average reader in your language might not know, or if those words carry particular significance, a glossary might be a good idea. The goal is to give the reader a helpful reference that helps them understand the meaning behind these words. A glossary always appears at the very end of the main text.

The back of a book can house all kinds of useful material, so the different reference types can get a bit confusing. We’ll break down where the glossary fits in among other back material.

Glossaries vs. endnotes

In a thesis or academic paper, the endnotes come before the glossary. Endnotes are a list of numbered comments that pertain to references within the texts. Unlike a glossary, which is organized alphabetically, endnotes are organized chronologically. In other words, they appear in the same order that the cited material appears in the book.

A glossary lists meanings and definitions for each term, while endnotes list additional context or background information relating to things the author talked about. This might include historical trivia, clinical data, or areas for further reading. So although glossaries and endnotes can look similar, they serve different purposes.

Glossaries vs. afterwords

Unlike glossaries and endnotes, which are formatted as lists, the afterword is a concluding prose section, meaning it will be written in paragraphs. An afterword is a space for the author to reflect on their inspiration behind the work and what they learned from writing it. They might compare the work to others in their field or to current events that relate to their topic.

An afterword is used in both nonfiction and fiction, but in fiction it’s more common to see it called the “author’s note.” This is especially common in historical fiction. The afterword, or author’s note, is where the author can discuss the real-life historical inspiration behind their novel and what they might have changed in the name of artistic license. A glossary, by contrast, defines terms that may have fallen out of use or be historically significant.

Glossaries vs. indexes

Similar to glossaries and endnotes, the index is a list at the back of an academic book. It’s usually the very last thing in the book, after the glossary, endnotes, afterword, bibliography, and anything else the author wants to stuff into the back matter. And like a glossary, it’s listed in alphabetical order. But that’s where the similarities end.

An index is used to list all of the topics and figures discussed in the book beside their relevant page numbers. That way if a reader wants to go back and review something again, they can go to the index. All they have to do is find the topic they’re looking for, and the index will tell them exactly what page it’s on. It’s more specific than a table of contents, which is listed at the front in chronological order. Because the topics of an index are listed alphabetically, the page numbers will probably be out of order.

What is the purpose of a glossary?

The purpose of a glossary is to give readers an easy reference for technical terms or cultural jargon that might be new to them. Having a place to quickly look up what a word means keeps them from having to run to the dictionary every time they come across a new word—or worse, give up on the book entirely.

If you’re very close to the topic of your book, it’s easy to forget that not everyone knows how to “speak the language” of this world, culture, or profession. A glossary helps your book appeal to a wider audience and introduces that audience to new ideas. It also helps boost your credibility in your profession.

When should you use a glossary?

A glossary of terms should be used in any nonfiction or academic work that has a lot of specific terminology pertaining to your topic. If you’re writing a medical dissertation, chances are there will be some words that non-medical people might not know. Or if you’re writing about a particular spirituality or religion, there may be terms inherent to that culture which those outside of it aren’t familiar with.

If you’re quoting older material, there may be some words that were once common but that have fallen out of use. A glossary is also useful if you’re writing about a merging of cultures—for example, a memoir about traveling to a new country. There may be phrases or specific terms that need to be translated for readers in your target audience.

Remember, the goal of including a glossary is to help orient the reader in your world. The last thing you want is to make them feel stupid! So when using unfamiliar terms, try to make that knowledge as accessible as possible.

Are glossaries only for nonfiction writers?

We’ve talked a lot about the role of glossaries in academic writing, but what about novels? Glossaries are used less commonly in fiction, but they do come up occasionally—mostly in fantasy or historical fiction, both genres where it’s common to use other languages as an element of worldbuilding.

Some fantasy authors, like J. R. R. Tolkien, create expansive worlds with a complex and rich history. Everything in his world is made up, including places, people, objects, even entire languages. In this kind of story, it’s a good idea to include a glossary. O. R. Melling’s novel The Hunter’s Moon mixes Irish Gaelic in with the English-language story, and so she includes an Irish glossary at the back of the book.

But you can use glossaries in other novels too, following the same rules as for nonfiction books. If you have a character who’s an astrophysicist, they might use some unfamiliar language in their work (in fact, it would be unrealistic for them not to). Or, your character might fall in love with someone from another culture, and through them the reader is exposed to some new words. In this case, you might want to include a glossary for your reader’s benefit.

How to correctly format a glossary

Some parts of a book have very strict formatting guidelines, particularly when it comes to citing sources. But a glossary is actually pretty straightforward.

First, make sure you’ve put your glossary in the right place. After the main body of the book, the back matter should go like this:

• Appendices

• Endnotes

• Glossary

• Bibliography

• Index

You might not need all of these parts in your book or research paper; just use the ones that are relevant to your project.

Then, put “Glossary” at the top of the page, followed by your list of key terms. Each term should begin on a separate line. Put the term in bold, followed by its definition in plain text. Pay attention to spelling, capitalization, and punctuation—it should appear the same way it does in the text.

Some words might have multiple definitions. You only need to include the meaning that you used in your book. Adding other definitions that don’t apply to your work might confuse your readers.

Finally, make sure that all your terms are in alphabetical order. You may find it easier to write out all the glossary entries and their definitions first, and then put them into alphabetical order once the list is complete.

Some useful book glossary examples

As you can see, glossaries can be used for a number of reasons in both fiction and nonfiction. Not all books need a glossary, but some benefit from this additional material. Here are a few examples of authors who have done it well.

The Lord of the Rings, by J. R. R. Tolkien

J. R. R. Tolkien’s groundbreaking fantasy novel is almost as famous for its prose as it is for its exhaustive supplementary material. The full collection includes no less than seven appendices, three indexes, and of course a glossary.

Tolkien does this to orient the reader in his meticulously crafted world, particularly its languages. As well as meanings, his glossary also includes the correct pronunciation for the range of Elvish words. (Note that this book has been released and rereleased many times, and so the exact content in each edition may vary.)

The Wild and Weedy Apothecary, by Doreen Shababy

In The Wild and Weedy Apothecary, herbalist Doreen Shababy explores the folklore and practical uses of the natural world. This nonfiction work is part recipe book, part approachable academic text.

She includes a glossary to define botanical and medical terminology that appears throughout the book, including things like Decoction (a method of preparing tea), Rhizome (an underground stem similar to a root), and Xylem (a plant’s vascular tissue). In doing so, the reader can refer to this throughout the text so they understand everything.

The Wrath & The Dawn, by Renée Ahdieh

The Wrath & the Dawn is another work of fiction—a retelling of the legend of Scheherazade and the 1,001 nights. The novel and its source material draw from rich Middle Eastern folklore, and the author uses language as a way to deepen the reader’s connection with this world.

The simple glossary at the back of the novel includes unfamiliar place names, endearments, types of clothing, and more. This allows the culture of the characters to shine through, even though the novel is written in English.

Glossaries help your readers navigate tricky concepts

There’s a lot to balance when you’re writing a book, from front matter to back matter, from student textbooks to thrilling novels. A glossary gives you one less thing to worry about. You don’t need to stop and explain every time you use scientific vocabulary, or clarify odd names in a story. Your reader has it all there for them to peruse as needed, before or after they begin reading.

Remember, not every book needs a glossary. It all depends on how specialized your topic is, and how much vernacular you’re introducing for the first time (this is where beta readers are really helpful). So go forth and spread knowledge!