Lol... I'm a non-native speaker of English from the other side of the Earth, and I've been using the word cover all my life.
I've always been thinking that, unless you write the song yourself, you're singing a cover. Even if you recorded the song first, you're doing a cover of the songwriter as long as he could sing.
Now you folks are telling me the word "cover" is inappropriate to use. Darn! My world is completely destroyed..