Usage and Grammar

Q. The other day a colleague asked me if it’s permissible to use the expression “a momentum” in a sentence. I told him that momentum is a noncount noun and isn’t normally used with articles (a or the). In fact, after a cursory search, I could not find such a usage online. However, the sentence “we’ve built up such a momentum” sounds correct (or at least not wrong) to my ear. So I later e-mailed him to say that it’s correct to use momentum without an article, but it isn’t wrong to use an article. Am I being wishy-washy?

A. My own cursory search shows that “a momentum” is correct in many contexts. So yes, you were wishy-washy—but wishy-washy is better than dogmatic when you’re wrong.