Below you will find guidance and examples of how to reference a dictionary in the body of your work and in the reference list at the end.
This source is not covered by the APA Style manual. You should also check with your lecturer when using these suggestions.
It is rare for a dictionary entry to have a named author. If it does, you should use the author's name as usual. If there is no named author you should use the entry title in place of the author's name.
("Crop Circles", 2007)
Title of entry. (Year). In Name of the encyclopaedia or dictionary (Volume number if any). Place: Publisher.
If you are using an online dictionary, replace Place: Publisher with Retrieved from URL.
Jejunum. (2003). In Merriam-Webster's dictionary (11th ed.). Springfield, MA: Merriam-Webster.
Acetone. (2012). In Macmillan dictionary. Retrieved from http://www.macmillandictionary.com/dictionary/british/acetone