Language acquisition is a contentious field of research occupied by cognitive and developmental psychologists, linguists, philosophers, and biologists. Perhaps the key component to understanding how language is mastered is explaining word acquisition. At twelve months, an infant learns new words slowly and laboriously but at twenty months he or she acquires an average of ten new words per day. How can we explain this phenomenal change? A theory of word acquisition will not only deepen our understanding of the nature of language but will provide real insight into the workings of the developing...