Q. How many times does it take for a foreign word to become familiar in a document? And does distance between occurrences matter? In reference to CMOS 7.55: “If a term becomes familiar through repeated use, it need be italicized only on its first occurrence. If it appears only rarely, italics may be retained.” This novel I’m working on has tons of foreign words in the dialogue that vary all over the place in frequency.
A. It’s not wise to quantify these things. You must use your judgment. Each word is a separate case. After all, non-English words that have an English cognate (activisme; simpatico; Milch; abreviación) are easily learned, but others might be very difficult. If you’re spending a great deal of time making decisions, consider making all non-English words italic all the time, knowing that some readers may find this tiresome and others helpful. However, as 7.55 also notes, “italics may not be appropriate for non-English words used as part of the vocabulary of a multilingual author, narrator, or character (as in fictional dialogue).” The writer and editor must work together to decide the best course.