The document discusses key terms and concepts related to the lexical approach to language learning. It defines a lexical chunk as any pair or group of words commonly found together, and defines collocation more specifically as a pair of content words found together. It provides examples of chunks that are and aren't collocations. The document also discusses Lewis' theory that native speakers have hundreds of thousands of lexical chunks memorized, and that learners acquire language through exposure to these chunks rather than individual words and rules. It notes one criticism of this approach is the lack of a detailed learning theory.