Changing some of the words used
From MoodleDocs
If you have installed Moodle and one to change one or two of the words Moodle uses (for example, if the word "course"/"courses" is not appropriate for your context), simply follow the "Making small customisations" instructions in the Translation instructions. You can define your "localised" strings in a separate file, which means they won't be overwritten when you upgrade Moodle.