Positive term for "unnegated"?

I read a paper which talks about "a logic formula in which each variable appears at most twice unnegated and once negated". The term "unnegated" is double-negative, which makes it slightly unclear. Is there a more positive term to denote a variable that is not negated?

I looked in an English thesaurus, but all suggestions seem out-of-context in logic.

You often see negative variables ($\neg x$) and positive variables ($x$). A literal is either a positive or a negative variable.

StackExchange Computer Science Q#20066, answer score: 6