Skip to main content

Style Manual Glossary

OWL logo

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

This glossary includes words and phrases that are useful when researching and citing sources. Many of these words are part of the academic metalanguage, or the specialized vocabulary used to talk about how research and citation is done in a Western academic context. Most of these terms appear in numerous locations throughout the OWL, but especially in our research and citation resources.

We chose these particular terms for two main reasons:

  1. Because these words and phrases are important to understanding how to use and cite sources.
  2. Because we have found that multilingual writers from around the world sometimes are unfamiliar with these terms, or use different terms to describe the same ideas.

We intend to add additional terms over time as more suitable candidates become apparent.



An initialism that stands for the American Psychological Association. The American Psychological Association is one of the foremost associations in the social sciences in western academia. The APA publishes its own citation style manual for publications, which is updated every several years.

Circa (c.)

The word “circa” means “approximately,” and it is used mainly with dates. For example, a writer might explain that the social media website Facebook was created circa 2004. Circa is used to give a rough approximation of when the event occurred when exact dates or times of year are not forthcoming.

Credible source

A publication, person, or other resource that provides accurate, clear, and reliable information about a particular topic, idea, or opinion. The credibility of a source directly affects the credibility of the writer citing information from that source. If a writer or student cites information from sources that are not credible, their paper risks losing credibility overall. Generally, the most credible and reliable sources are those published in academic peer-reviewed journals. The least credible, most unreliable sources are sources written by people with no background or education in the topic or sources that can be easily edited by almost anyone (such as Wikipedia or social media). Different fields of study have different requirements for what constitutes a credible source, so writers should always consult the OWL, an instructor, or a knowledgeable advisor about the rules for credible sources in her or his area of study.

Common knowledge

Information that has become so mainstream that is so widely known in the public domain that there is no need for it to be cited. One example is the mass-energy equivalence formula (E = mc2). As this equation is widely known, there is no need to cite Albert Einstein’s original research in which he developed the equation.


A citation in a works cited or references page at the end of a document. If a writer uses eight different sources in a paper, they should be cited within the paper wherever the information from those sources is used. Each of the eight sources should also be given an entry in the works cited or references page at the end of the document. The format and information included in the entry depends on the style manual the writer is using.

Footnotes and Endnotes

Extra information (usually non-essential citations or extra contextual information) that the writer does not include in the main text of the document. Footnotes and endnotes are usually indicated within the text of the document by small superscripted numbers or letters (i.e., like this123). These small numbers correspond to the citation or explanation at the bottom of the page (for a footnote) or at the end of the document (for an endnote).


The space at the top of an electronic document. Most style manuals require the writer to put certain types of information in the header, such as last name and page number.


The space between the margin and the text in a document. Indentation is usually created in electronic documents by using the space bar or the “tab” key on the keyboard. In many styles, the first line of a paragraph is indented by one tab (five spaces). Indentation is also important when formatting long quotations, formatting works cited/reference entries, and formatting outlines. 

Kindle Books

A type of electronic book. A “Kindle” is an electronic reading device sold by the company Amazon. Kindle books exist in a different format than other electronic books, however, as, readers can download a free version of a Kindle e-reader application on almost any electronic device in order to read a Kindle book.


An initialism that stands for the Modern Language Association. The Modern Language Association is one of the foremost academic associations in literature, linguistics, and the humanities in western academia, and they publish their own style manual for publications, which is updated every few years.

Multi-volume Work

A book or publication that is published in two or more separate pieces. A publication may have multiple volumes because it has too many pages for just one piece. This is usually the case with encyclopedias. A publication may also have multiple volumes because each piece is published at different times throughout the year. It is usually the case that academic journals are published multiple times each year.


The way pages are assigned to a publication by the editor or publisher. Pagination is especially important for a multi-volume or multi-issue journal. Generally, the editor or publisher assigns pagination either by starting at page 1 for each volume or issue or by continuing the page count throughout many volumes or issues. In the second method, the first page of a second volume of a publication will not be labeled as page one. For example, if volume one ended with page 340, then the first page of volume two would be labeled page 341.


To restate another person’s idea in one’s own words. A paraphrase must differ substantially in vocabulary and word order, but should still retain the content of the original idea. Writers who make a paraphrase should cite the original author to avoid committing an act of plagiarism.

Parenthetical Citation

Identifying information from a certain source that a writer includes in the body of a text to signal to the reader where a certain argument or piece of information came from. This information is presented inside a set of parentheses. Different style manuals require different information in a parenthetical citation. Different style manuals also state where the parenthetical citation can and cannot be within a sentence.

Section Heading

A short, precise title for a section contained within a larger document. Some style manuals and reports require section headings to make it easier for the reader to find information quickly. Section headings may or may not be included within a table of contents.

Signal Phrase or Lead-In Phrase

A word or set of words that introduce information from someone else. A signal or lead-in phrase comes before a quotation, paraphrase, or summary, and includes information like the author’s name, the title of the source, or the year it was published. The word or words signalto the reader that the writer is using someone else’s ideas, and lead into the new information.

Signal Verb or Lead-In Verb

The active verb included in a signal phrase or a lead-in phrase. Depending on the style manual the writer is using, this verb may need to be in the present tense, past tense, or a conditional tense. Writers should select signal verbs with care to accurately represent the source they are citing.

Style Manual

A list of rules about how to research and write for academia or publication. There are many different style manuals, and each has different rules for the style of writing, citation, and overall format used in a paper. Some of the most well-known style manuals include those published by the APA and MLA.


A message or entry on the social media website Twitter. Tweets are limited to 280 characters (letters, numbers, symbols, punctuation, and spaces). Some style manuals give specific ways to cite tweets as sources.