I found the term in The Limits of Realism (Tim Button) (2013) on page 2:
We are, then, looking for an argument that forces realists to consider semantic questions. A natural place to look is in the discussion of meaning scepticism that took America by storm in the 1960s onwards, culminating in Hilary Putnam's model-theoretic arguments against a certain kind of realism. This is my entry point to the realism debate.
Apparently, there's a book named after it as well. I know what scepticism means, but what does meaning scepticism mean exactly?