versus

It is pronounced fully, and so should it remain. For example, good v. evil would be pronounced "good versus evil" and man v. nature would be pronounced "man versus nature."

That that pronunciation is occasionally inconvenient is attested by the variant v., pronounced "vee," as in "Roe vee Wade."

What convenience does not excuse, on the other hand, is the strange truncation "vers." It would be corrupt even if the language did not already include the word verse.