When the dictionary has an author or authors (thus not editor(s) or compiler(s)), the text reference and entry in the reference list are handled the same as a book with an author.
Peters, P. (2013). The Cambridge dictionary of English grammar. Cambridge University Press.
The term morpheme refers to “the minimal unit of linguistic meaning, a form to which a meaning may be attached” (Peters, 2013, p. 151).
Use the editor’s surname in the text reference, the same way as a text reference for a book. In the reference list entry, after the surname(s) of the editor(s) or compiler(s) qualify it with the appropriate abbreviation for editor(s) or compiler(s).
VandenBos, G. R. (Ed.). (2015). APA dictionary of psychology (2nd ed.). American Psychological Association.
The APA dictionary of psychology defines obsessive-compulsive disorder (OCD) as ... (VandenBos, 2015).
Brokaw, D. (1990). Character and personality. In R. J. Hunter (Ed.), Dictionary of pastoral care and counselling (pp. 136-137). Abingdon Press.
When an online dictionary is updated over time and not archived, include a retrieval date in the reference list entry.
Merriam-Webster. (n.d.). Culture. In Merriam-Webster.com dictionary. Retrieved September 9, 2019, from https://www.merriam-webster.com/dictionary/culture
Culture refers to the “customary beliefs, social forms, and material traits of a racial, religious, or social group” (Merriam-Webster, n.d.).
Merriam-Webster. (n.d.). In Merriam-Webster dictionary (Version 4.3.3) [Mobile application]. Retrieved from http://www.merriam-webster.com/apps