If you need to define a word in your paper, the definition usually comes from a glossary in the back of a book. To properly attribute this definition you will need to cite it according to the American Psychological Association (APA) style guidelines.
In-text Citation
Cite glossary terms in the in-text citation with the author and copyright date in parentheses. If the glossary is written by an organization instead of an author, include the organization's name. For example:
According to The Seagull Reader, alliteration is the "repetition of words with the same consonants within a line of poetry" (Kelly, 2001).
Works Cited
The works cited entry of a glossary term should include the title of the entry, capitalizing the first word of the title, subtitle and all proper nouns or names. End this title with a period. Next, add the year of publication in parentheses, ending with a period. Then include the word "In," followed by the title of the book italicized, the edition number in parentheses followed by a period, then place of publication followed by a colon, then the publisher.
For example:
Kelly, Joseph. (2001). Alliteration. In The Seagull Reader: Poems. New York: W.W. Norton & Company, Inc.
Note that "The Seagull Reader: Poems" should be italicized.