How to Cite a Definition From an Online Dictionary

You never know when you might find yourself needing to define a word like "mizzle-shinned," one of the Oxford English Dictionary's many words of the day. When you do, it's helpful to the reader to both offer a definition and information about where that definition came from. Citing online dictionaries differs from other Web-based sources because they typically don't have authors. Instead, most style guides suggest you use the word you define as the first component of your citation, followed by website and date information. Some, but not all, style guides also require URL information.

Modern Language Association (MLA) Style

Students writing about literature, who often use MLA format, could find themselves defining unusual words. To correctly cite a definition from an online dictionary in MLA format, include both the original source and the website information. This example shows the proper formatting:

“untenable.” Merriam-Webster Dictionary. New York: Merriam-Webster, 2004. Web. 13 Feb. 2015.

This citation includes the publisher information for the print copy of the Merriam-Webster dictionary, as well as the URL and date the definition was accessed. According to Merriam-Webster’s website, the following example is also an acceptable MLA style citation:

“untenable.” Merriam-Webster, 2015. Web. 13 Feb. 2015.

The in-text citation for this Works Cited reference would read: (“untenable”).

American Psychological Association (APA) Style

Students writing in fields like psychology or social sciences commonly define words the reader may not know the definitions of without referring to a dictionary. APA style also uses the entry title of the dictionary as the first item in the citation:

pathology. (n.d.) In Encyclopedia Britannica Online. Retrieved from

Note that there is no period after the URL at the end of the citation. Use (n.d.) if there is no date specified in the entry; otherwise, use the year of online publication, often found at the bottom of the page, in parentheses.

The in-text citation for this example would read: (“pathology,” n.d.).

Chicago Manual of Style (CMS)

The Chicago Manual of Style is a comprehensive guide used by many publications. According to the Purdue Online Writing Lab, scholars in the areas of history, literature and the arts tend to use Chicago's "notes-bibliography" system, while its "author-date" system is used more commonly in the social sciences.

In either system, you always have the option to reference the name of the dictionary and edition along with the definition in the running text. According to the website of the Simon Fraser University Library, Chicago discourages including well-known dictionaries in the reference list or bibliography; however, including a complete bibliographic entry for less-common dictionaries is recommended.

In the author-date system, an in-text citation linked to a specialized dictionary in the reference list includes the name of the dictionary and edition number in parentheses if not simply included in running text.

If your professor asks you to use the notes-bibliography system, create a footnote. Chicago lists the dictionary’s name as the first item in the footnote entry, followed by the abbreviation “s.v." (for the Latin phrase "sub verbo"). Here is an example:

  1. Merriam-Webster, s.v. “rhythm,” accessed January 2, 2015,

The bibliographic entry at the end of your paper is written in a similar format, as in this example from the Simon Fraser University Library:

Grove Music Online, s.v. “Sibelius, Jean,” by James Hepkoksi, accessed January 3, 2005,

Associated Press (AP) Style

AP style is typically used by journalists, and definitions from online dictionaries are cited within a sentence. You cite an online dictionary in AP style like this:

The Oxford English Dictionary online defines “mizzle-shinned” as “having one’s legs red and blotched from sitting too near a fire.”

You identify the source of the definition in the text, but you don't need to include a formal bibliographic citation.

Need help with a citation? Try our citation generator.

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