Words are often regarded as “slippery customers” (Labov, 1973). First, it is difficult to come up with a fixed content that seems to apply across all uses of a single word (Wittgensten, 1953). Second, the meaning of a word is subject to wider contextual constraints beyond the company it keeps with other words within a sentence. Third, the assumption that a word means a fixed thing is at odds with the fact that word meaning shifts over time, as do the objects a word refers to. Taken together, theories of word meaning need to be able to account for the intuition that words have content associated with them, while allowing for variation in how a word is used in context, and how word meaning can change over time.