I’ve been interested in linguistics for a while now, and I’m pretty sure it’s what I want to major in. I’ve been teaching myself about it by:
-Completing three linguistics MOOCs
-Participating in contests and spending time preparing for those contests (North Amer. Computational Linguistics Olympiad, Vocal Iconicity Challenge)
And, of course
-Reading as many linguistics books and blogs and watching as many videos as I can
I’m also teaching myself Klingon, but that’s not something I want to tell admissions officers, haha.
So, in short, can I call it an EC? I do a few other ECs that are language-related (tutoring Hebrew, a volunteer position with Spanish/English bilingual stuff), but this is a distinct thing and it’s incredibly important to me, so I want to include it somewhere.
Bump on your behalf. I have the exact same question as you except I spent thousands of hours teaching myself coding and developing software.
Can someone please advise us?
The MOOCs and the contests can certainly be listed as activities. You can create one activity called “Linguistics” and put the details in a bullet list in additional information if you want to. The reading books and blogs, not as much. But if it makes sense to include somehow in your common app essay or a supplemental essay requested by a college, then put it there (eg, “Why College X?” “I am very interested in the linguistics course offerings, especially blah blah.”). I’d probably leave the Klingon out, too. 
As an aside, one of my kids did the NACLO. She didn’t really study for it before, and doesn’t have much of a knack for it anyway. But it was interesting, and she enjoyed her day on the college campus meeting professors and other students on the day she took it.
@intparent Thanks so much for your response! That makes a lot of sense.
I enjoyed NACLO very much! It’s definitely a cool thing in terms of exposure to new environments and academic disciplines. And if you’re the kind of kid who digs puzzle-solving, there’s no better way to spend a morning!