This chapter examines how humans convey thoughts, feelings, and more to others. It is an overview of semantics, the study of meaning, and lexical semantics, the study of word meaning. It covers how dictionaries and other authoritative reference works deal with meaning and what the implications are of having people or government arbitrate what’s considered proper. It provides information about how words are defined and encourages readers to try drafting definitions of words. It discusses how meanings of words change over time and how new meanings arise, and how meanings of words within a language vary from region to region. It looks at the ways philosophers and linguists have analyzed meaning.