A semantic cluster refers to a group of words or concepts that are closely related in meaning and often used together in language. These clusters can be found in various forms, such as synonyms, antonyms, hyponyms, or collocations. They provide a deeper understanding of a particular topic or idea by presenting a range of related terms that help to clarify and expand upon its meaning. Semantic clusters are essential in language processing and can aid in effective communication by providing a rich network of interconnected words that enhance the overall understanding of a text or conversation.