Compose the complete citation for your bibliography, because every in-text citation needs to correspond to a detailed reference on your Works Cited list at the end of your paper. Write the word you are defining and put it in quotation marks. Write the abbreviation "Def." to state you are citing a definition. Provide the name of the dictionary or encyclopedia where you found the definition, italicized. Give the edition and the year of publication. Separate the different details using periods. For example: "Life." Def. Merriam-Webster Collegiate Dictionary (italicized). 11th Edition. 2003.
Define the word you want in your text by putting the definition you found in quotation marks. Then, between parentheses, cite the dictionary or encyclopedia and the exact page where you found the information. For example: Life is "the quality that distinguishes a vital and functional being from a dead body" (Merriam-Webster 131).
Quote the definition word for word in your paper, and identify the dictionary or encyclopedia where you found the information in your sentence. For example: As the Merriam-Webster Collegiate Dictionary defines it, life is "the quality that distinguishes a vital and functional being from a dead body." Then the reader can go to the bibliography at the end of your paper to find the relevant details.
Even though nothing changes in your in-text citation of the definition when you are referencing an online dictionary or encyclopedia, you do need to adjust a few things in your detailed citation for your bibliography. There, include the term in quotation marks, the name of the online dictionary, italicized, the name of the publisher and date of publication. Write the word "Web" and provide the date that you came across the definition. For example: "Life." Merriam-Webster.com. Merriam-Webster, 2011. Web 5 July 2011.