The MLA is a style guide for writing research papers commonly used in high schools, colleges and universities. The acronym stands for "Modern Language Association." The goals of the MLA are to "strengthen the study and teaching of language and literature." One of the ways they do this is by standardizing the way you write and how you use your words. In MLA format, for example, foreign language words are italicized. However, there are many exceptions to this rule, and such is the case with Latin.
Use a dictionary to determine whether the Latin word or phrase in question has been adopted into the American English language. Merriam-Webster's Collegiate Dictionary (11th ed.) is the largest and most popular dictionary for college students.
The MLA (7th ed.) points out three common Latin abbreviations that are never italicized: "e.g.," "et al." and "etc." However, when spelled in full, they are italicized. For example: "e.g." but "exempli gratia."
However, if the word or phrase in question is not in the dictionary, italicize it in your research paper. Choose a font in which the italic style is significantly different from the regular style. Although a little old-fashioned, you can almost never go wrong with Times New Roman.