Much of my work concerns an epistemological question: What is it to understand a word—to “possess the concept” it expresses? My view is that the sort of understanding you need to have, in order to do something with a word, depends on what you want to do with it—what type of speech act you’re trying to perform, or what sort of sentence you’re using the word in. So there’s really no answer to the epistemological question, put that baldly. But there are illuminating things to be said about the relations among different kinds of understanding.
Recently I have examined these questions as they show up in theories of quotation and in theories of concept possession. I'd be happy to discuss supervising any students interested in those topics or more generally, topics in philosophy of language (and some areas of epistemology).