Extracurricular is one word.
The word extracurricular comes from the two words " extra & credit ". So since there is only one ful word that is in the word " extracurricular " extra is the root word.
* extraordinary * extraterrestrial * extracellular * extrasensory * extravaganza * extravagant * extracurricular * extradite
In (proper!) UK English, it's written with a hyphen. I don't know about US English or other variations of English. If you Google it, you'll find all three forms widely used!
It is two words. Writing it as one is acceptable in the UK and is referred to as a "Britishism." But in American grammar, it is always two separate words.
Extracurricular
Some examples of words with the affix "extra-" are extracurricular (outside of the regular curriculum), extraordinary (beyond the ordinary), and extravaganza (a spectacular event or display).
Two words - "one day".
Skiing is an extracurricular activity. Reading outside of school is extracurricular.
They are two words conjoined to be one.
"After school" is typically written as two words.
It is two words take it from a 7th grader