What is "gender"? What kinds of definitions have been advanced or implied for this perplexing word? How have thinkers - in fields as diverse as anthropology, history, literature, philosophy, psychology, science studies, and sociology - helped to define and even invent this category that we call "gender"? How have these definitions changed the way we think? What kinds of problems have these definitions created? In this module, we will analyse various moments in intellectual history when there has been a struggle over the meaning of "gender" (and seemingly related terms like "sex" and "sexuality") in order to understand the term's function as a category of analysis.