The document discusses synonyms and antonyms, which are words that are similar or opposite in meaning. It provides definitions of synonyms as words that mean the same or nearly the same, and antonyms as words that mean the opposite or nearly the opposite. Examples are given and tips provided for learning synonyms and antonyms, such as using vocabulary trees and flashcards. An activity asks the reader to provide a synonym and antonym for given words. Links to additional resources on synonyms and antonyms are also included.