Word learning is typically studied as a problem in which children need to learn a single meaning for a new word. And by most theories, children's learning is itself guided by the assumption that a new word will have only one meaning. However, the majority of words in languages are polysemous, carrying multiple related and distinct meanings. Here, we consider the implications of this disjuncture. As we review, current theories predict that children should struggle to learn polysemous words. And yet research shows that young children readily learn multiple meanings for words and represent them in qualitatively similar ways to adults. Moreover, polysemy may facilitate word learning, by allowing children to use their knowledge of familiar meanings of a word to learn its other meanings. These findings motivate a new perspective on word learning that recognizes polysemy as a fundamental feature of language, instead of treating it as an edge case.