is not a plural,
and its singular is not
This is more of a verbal error than a written one, thus far, largely because in writing, everyone tends to use "vs." -- but it's one I keep hearing more and more often, from people who should know better. "Pirates vs. Ninja" gets pronounced as "Pirates verse Ninja".
[Let's see what Your Obedient Serpent's Grammar Guide says about this: ]Let's see what Your Obedient Serpent's Grammar Guide says about this:
Yes, both "Verse" and "Versus" can be abbreviated as "vs.", but they are not interchangeable!
Stop it at once. Where did you learn this?