Only terms, words, or phrases that have special or unique meanings in the study are defined.
Important words in the title (such as the variables), Technical terms used in the research paper, Words for treatments and measurement (data analysis terms, etc.) should be defined.
Define terms technically, operationally, or both.
If the terms are from dictionaries, books, encyclopedia, other publications, and even websites (technical definition), acknowledge the source.
If there are uncommon acronyms, include them; spell them out and give the meaning.
Definitions should be short, clear, and unambiguous.