6. Most words formed with a prefix (e.g., co, anti, extra, micro, over, pre, sub, post) are not hyphenated (e.g., subdivision, extracurricular, postgraduate). Exception: if the prefix comes before a capitalized word (proper noun) it must be hyphenated (e.g., mid-April, pre-World War II).

Is it extra curricular or extra curricular?

Extracurricular is a combination of the Latin prefix extra- meaning "on the outside" and the word curriculum, meaning "a running, course, career." Something that is extracurricular is on the outside of your course or career. When you get involved in an extracurricular activity, you are going outside of what's expected.

How do you write extracurricular activities on a CV?