A dictionary is a book or digital resource that lists words alphabetically and explains what they mean. When you encounter an unfamiliar word while reading, you can look it up in a dictionary to find its definition, discover how to use it correctly, and sometimes learn where it came from.

Dictionaries show you how words relate to each other, which meanings are most common, and how language actually works. A good dictionary might tell you how the meanings and uses of certain words have changed over time.

Think of a dictionary as a map of language. Just as a map shows you where places are and how to get there, a dictionary shows you what words mean and how to use them. When you're writing and need exactly the right word, when you're reading and stumble across something puzzling, or when you're curious about language itself, a dictionary is where you turn for answers.