In most cases you should avoid using dictionaries and encyclopedias as cited sources in your papers. However, there may be some cases where it would be appropriate. This is how you would do it in those cases.
If you have an author for the entry use their name for the in-text citation and at the start of your reference list entry. When you don't have an author, which is often the case for these types of sources,follow the guidelines on page 176 of the APA Manual under example 6.15. There it states that “when a work has no identifiable author, cite the first few words of the reference list entry.”
Example in-text citation without an author:
ALRs, Encyclopedias, Law Reviews, Restatements, & Treatises: Legal EncyclopediasAcademic Guides: Evaluating Resources: Encyclopedias
The Charleston Index is one method for determining the mortality rate for patients with multiple diseases (Comorbidity, 2012).
Example reference list entry for the above in-text citation (note: also an example of an online reference source):
Comorbidity. (2012, November 24). InWikipedia, The Free Encyclopedia. Retrieved 21:50, November 27, 2012, fromhttp://en.wikipedia.org/w/index.php?title=Comorbidity&oldid=524649802
Note: This is an example using Wikipedia, which is updated constantly. That is why there are more details than usual for the publication and retrieval date and time. For non-wiki reference works less detail is required.
Example in-text citation with an author:
Amnesty International was established in support of "prisoners of conscience" (Wong, 2012, p. 65).
Example reference list entry for the above in-text citation (note: also an example for a print source or source with a doi):
Wong, W. (2012). Amnesty International. In H. Anheier, & M. Juergensmeyer (Eds.),Encyclopedia of global studies.(pp. 65-67). Thousand Oaks, CA: Sage. https://doi.org/10.4135/9781452218557.n19