Synonyms & Antonyms are an integral part of grammar. Primarily it enhances the vocabulary. It also encourages replacing the old words with new one & thus brings newness in saying something. Exploring new words is very motivating & interesting. Besides, using different synonyms & antonyms attracts the readers and listeners. Hence the speaker can leave an excellent impression. It also spices up the conversation.
But all this can only happen when these are used effectively & at the right place. For example the synonyms for the word student are pupil, scholar, undergraduate, learner etc. The word student means a person studying in a school or a college while pupil means a person or child studying in school or privately with a teacher. Their usage will be clearer with the following example. I am an engineering student. He is a pupil of famous singer, Lata Mangeshkar. Similarly the word scholar means someone who has expertise in some field. Raman is a maths scholar. This means that Raman in expert in Maths. Thus the reader or speaker should ensure that the synonyms are used efficiently.
Likewise, using the antonyms effectively brings vividness in speaking & writing and also makes them vibrant. The antonyms are basically used to show contrast. The distinction can be for time such as day- night or morning – evening, for colours like light – dark, dull – bright, for comparison like big – small, tall- short, for describing personality ugly- beautiful, elegant- inelegant etc.
Therefore the appropriate use of Antonyms & Synonyms makes the text & speech striking.