This document discusses native speaker intuitions about words and lexical categories. It notes that we intuitively understand that words exist as independent linguistic units, even though there is no clear acoustic evidence delineating words. It then discusses how words can be categorized into lexical categories or parts of speech based on semantic definitions, morphological evidence like suffixes, and syntactic evidence like distributional tests that show how words can be inserted into frames depending on their category. Overall, the document examines how we intuitively understand words and lexical categories even without clear-cut evidence, drawing on semantics, morphology and syntax.